Since this thread covers more than one manufacturer, I won't be adding a poll here. Feel free to post your personal experiences with any ammo that fits the overall description below.



This is a catch-all post for discussion of heavy (68gr+) OTM ammo such as:



* Hornady 75gr OTM



* HSM 75gr OTM



* 77gr loads such as Mk262



* Wolf 75gr



* Prvi 75gr



* etc.
THIS IS A REVIEW THREAD, NOT A DISCUSSION THREAD. PLEASE KEEP YOUR POSTS CONFINED TO YOUR OWN PERSONAL EXPERIENCE WITH THIS AMMO.
The type of information I'm looking for is something along the following:



* Ammunition used



* Muzzle velocity (if you have it)



* Your rifle (barrel length/twist rate)



* Bullet accuracy



* Does the bullet fragment (water tests or references to ballistic gelatin data)

* Reliability problems



* Anything else that's useful to know

AIM graciously sent me a small sample of ammo to evaluate, so this is
this post will include some data that may be of use for you guys. This
first report won't include any shooting data; I haven't had time to go
to the range yet. Instead, I pulled 10 bullets, weighed the powder and
bullets, measured the bullets and loaded ammo, and took some pics.



The loaded ammo looks pretty much like any other Wolf ammo: Grey polymer coating, primer sealant, no neck sealant:










Pulling
the bullets showed that they are definitely bi-metal, as they were
strongly attracted by a magnet. I plan to shoot these into some water
jugs to determine if they will fragment. As You can see, the bullet is
not a true OTM round as the bottom of the bullet exposes the lead:








For
comparison, the bullet on the left is a Hornady 75gr OTM bullet, T1
variant. The bullet looks a little weird because it was tarnished a
little having been left in the garage for a few months.



Here's the view of a sectioned bullet:








Nothing
much to say - it reminds me of the 62gr Silver Bear I sectioned several
years ago. Minimal cavity for the hollow point. That bullet did
fragment, however, so we'll have to see if this one does as well.





The powder is a short-cut extruded:








On to the data.



Powder weight

21.1

21.1

21.3

21.3

21.0

21.0

21.1

21.1

21.3

21.2



HIGH: 21.3

LOW: 21.0

E.S.:0.3

AVG:21.15

StdDev: 0.12



I
thought the powder charge is fairly consistent, pretty much what I
would expect from factory ammo - maybe a little better even. The weight
of the powder charge indicated a pretty fast burning powder. Based on
the chronograph results I've seen so far would put this powder
somewhere around Alliant Reloader 7, maybe even faster. This is
speculation though.



Bullet weight

74.0

74.7

74.3

74.0

73.5

74.2

73.7

73.2

73.9

73.8



HIGH: 74.7

LOW: 73.2

E.S.:1.5

AVG:73.93

StdDev: 0.42



The variance in bullet weight is definitely more than I expected. An extreme spread of 1.5gr.



Bullet length

0.939

0.941

0.948

0.945

0.939

0.940

0.947

0.949

0.948

0.940



HIGH: 0.949

LOW: 0.939

E.S.:0.010

AVG:0.9436



I
don't have one of those little tools that allow you to measure the
length of the bullet from a specific spot on the ogive, so this is the
overall length of the bullet only. The ES of 0.010" is very good, about
the same as Hornady 75gr OTM.



Loaded ammo length

2.238

2.233

2.240

2.241

2.240

2.247

2.241

2.238

2.240

2.244



HIGH: 2.247

LOW: 2.233

E.S.:0.014

AVG:2.2402



The
average length of 2.240 will not present a problem for loading these
into a standard AR mag. 2.260" is the max length for a .223 round to
fit into a magazine. The ES of 0.014" is about on par with the
variation on the length of the bullet itself, and I would say that
seating depth is very uniform.



I finally had a chance to do some informal testing on this ammo
using some water jugs to test fragmentation. I know there was one other
person that shot the ammo into water-filled antifreeze jugs, and no
fragmentation was noted. I'm not sure of the distance involved.



I
had 6 milk cartons to play with, and I thought 3 lined up would be
enough; I was wrong. It turns out that the ammo did appear to fragment.
The distance of the shot was 15 feet:








As
you can see, the tip of the bullet is gone, and the lead core was
pushed out. There were a few lead fragments left in the bottom of the
milk jug. I *think* I found these in the second jug, but I'm not sure.
The first jug had a near punctate entrance and exit hole, the third jug
appeared to have been shredded somewhat - it would agree with the
fragmentation I saw. Unfortunately, I should have used more jugs. Oh
well.



The second shot was pretty much like the first, although I found the lead core on this one:








Notice
the jacket fragment stuck on the surface of the milk jug. Here is a
closeup of the fragments of what I was able to find. The piece of
jacket stuck in the plstic was the very tip of the bullet BTW:








The
ammo did fragment in this particular test, but I caution anyone to
extrapolate too much from this test. Even though I saw the bullet
fragment, I would expect the fragmentation distance to be fairly short.
This is just my best guess; steel jackets are inherently tougher, and
even a slight loss of velocity might mean that the bullet wouldn't
fragment. If I collect a few more water jugs, I might try some longer
distances. The second unknown is: when the bullet does fragment, how
soon does it do so? If the yaw cycle starts too late, it may not be a
good choice. Silver Bear 62gr JHP gave me the same results when I
tested it years ago, but the same caveats apply.



The only way to
find out for sure would be to shoot some ballistic gelatin to eliminate
the unknowns. But one thing is certain: In the words of O_P - shooting
stuff is fun!

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.
Hornady 75 grain 223 TAP versus 75 grain MATCH

Hornady’s
75 grain BTHP Match ammunition (part #8026) is loaded with the same 75
grain boat-tail hollow point bullet that is available from Hornady as a
reloading component (part #2279). The case mouth of the Match load has
a slight taper crimp on it which puts a small crease in the bullet
itself. The Hornady 75 grain 223 TAP load (part #80265) uses the same
75 grain BTHP bullet as the Match load with the addition of a
cannelure. Unfortunately, the cannelured version of this bullet is not
available (to the general public) as a reloading component.


Previous
lots of both the Match and 223 TAP load have been charged with a
short-cut, charcoal colored extruded powder, while the most recent lots
that I have purchased (including the ones used in this test session)
are charged with a greenish/yellowish colored short cut, extruded
powder resembling those powders found in the Hodgdon lineup of powders.
Both loads use traditional brass cases and the caseheads from both
loads are head-stamped “Hornady 223-REM” and neither load appears to
have sealed nor crimped primers. The case mouth of the 223 TAP load is
crimped into the cannelure of the bullet.


previous powder





recent powder





Chronograph
testing was done using an Oehler 35-P chronograph with "proof-screen"
technology. All strings of fire consisted of 10-shots each. All
velocities listed below are muzzle velocities, as calculated from the instrumental velocities using Oehler’s Ballistic Explorer software program.


Accuracy
testing was performed using my 24” Krieger barreled AR-15. Shooting was
done from a bench-rest at 100 yards. All groups were 10-shot groups.
Prior to testing the Hornady ammunition, I fired a 10-shot control
group using handloaded 55 grain Sierra BlitzKings. That group had an
extreme spread of 0.63”.

Starting
with the Hornady 75 grain 223 TAP load, I fired five, 10-shot groups
from 100 yards and used the best three groups for analysis. Those three
groups had extreme spreads that measured:





1.17”


0.87”


1.05”





for a 10-shot group grand average of 1.03”.  The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group that had a composite mean radius of 0.32”.
best 10-shot group of 75 grain 223 TAP

In
the same manner described above, I obtained three 10-shot groups of the
Hornady 75 grain Match load. The extreme spreads of those groups
measured:





0.89”


1.03”


1.16”





for a 10-shot group grand average of 1.03”!  Over-laying those three groups on each other using RSI Shooting Lab yielded a 30-shot composite group with a mean radius of 0.36”.
best 10-shot group of 75 grain MATCH

For
additional comparison, I obtained three 10-shot groups from 100 yards
using hand-loaded Hornady 75 grain BTHP bullets. The extreme spreads of
those groups measured:





0.78”


0.71”


0.52”





for a 10-shot grand average of 0.67”.  The mean radius formed from over-laying those three groups on each other was 0.23”.
best 10-shot group of hand-loaded 75 grain BTHP

Here’s a pic of the composite groups side by side for comparison.

Lastly,
in a tribute to the Internet Commando, I fired two, 3-shot groups in a
row from 100 yards using the control load. Both groups were sub-QUARTER-minute-of-angle.



Here's a compilation of the 100 yard accuracy testing results of all
the factory loaded ammunition tested for this thread that uses a
Hornady 75 grain BTHP bullet.












 
 

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.





MK262 comparison





As
far as I am aware, the only other 5.56mm NATO pressure round loaded
with a “heavy” OTM bullet besides the Hornady 5.56 TAP round (that is
currently commercially available) is the Black Hills MK262 load. One
can’t help but wonder how the two compare.



The MK262 round is
currently loaded with the Sierra 77 grain MatchKing bullet with a
cannelure. Looking through my chronograph records shows that the MK262
round has a slightly higher
velocity compared to the 5.56 TAP round when fired from a 20” NATO
chambered barrel and nearly identical velocities when fired from both
16” and 14.5” barrels. The overall standard deviations of both loads
are also quite similar.












The
external ballistics of the two loads are virtually indistinguishable
out to 250 yards. The conservative ballistic coefficients used for the
graph and tables below were derived by testing at 200 yards by Rick
Jamison.














I
tested the accuracy of the Black Hills MK262 load using the same Colt
20” HBAR that was used to test the Hornady 5.56 TAP load. This barrel
is NATO chambered, chrome lined and has a 1:7” twist and has repeatedly
proven to shoot very well for a factory barrel. (While a match barrel,
with say a Wylde chamber, might produce tighter groups than this
barrel, the idea here was to test the MK262 load for its relative accuracy compared to the 5.56 TAP load.)   The testing was done from a bench-rest at 100 yards.



My usual procedure of obtaining three, 10-shot groups from 100 yards and overlaying those groups on each other using the RSI Shooting Lab software program was continued with this test.    



The
previous control loads fired from the Colt HBAR using a standard
handload with a 77 grain Sierra MatchKing had a mean radius of 0.32”
for the 30-round composite target. The 30-round compostite target from
the MK262 load produced a mean radius of 0.42”.   For comparison the mean radius of the previous 30-round composite target from the 5.56 TAP load was 0.46” giving the MK262 load a very slight  edge in accuracy.



The 10-shot groups measured:



Control load––-1.05”, 1.07”, 1.10”



MK262––––––––-1.20”, 1.34”, 1.37”



5.56 TAP––––––1.16”, 1.38”, 1.45”







 

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.





Hornady's 75 Grain Practice Ammunition





Hornady’s
75 grain practice ammunition uses a Berdan primed, steel case instead
of a brass case to reduce the cost of the loaded cartridge. The round
uses Hornady’s 75 grain BTHP bullet with a cannelure (referred to as
the T1C here on AR15.com.) The round is charged with ball powder and
has a muzzle velocity similar to Hornady’s 75 grain TAP FPD. Fired from
my 20” Colt government profile barrel with a NATO chamber, a 10-shot
string had an average muzzle velocity of 2,646 fps with a standard
deviation of 9 fps.








The
steel case employs the heaviest amount of bullet-pull I have ever
encountered in a 223 Remington case. I was unable to remove a bullet
from the case using Dillon’s kinetic bullet puller, so I chucked a Lee
collet bullet-puller into my reloading press and attempted to pull the
bullet. I still couldn’t get
the bullet out of the case! At that point, I had to resort to more
primitive means to get the bullet out of the case.

I
tested the accuracy of the 75 grain practice round following my usual
procedures. Using a free-floated 20” Colt HBAR and shooting from a
bench-rest from 100 yards, I obtained three 10-shot groups and
over-layed them on each other using RSI Shooting Lab.
The 30-round composite group had a mean radius of 0.47”. While not as
accurate as Hornady’s 75 grain TAP FPD, accuracy was on par with the 75
grain 5.56 TAP load.

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.
Black Hills 75 grain Match HP Ammunition:  blue box versus red box

The
difference between Black Hills’ red box and blue box ammunition lies
primarily with the brass case. Red box ammunition is newly manufactured
using virgin brass. Blue box ammunition is referred to as
“remanufactured” because is uses once fired brass that has been
resized. This enables Black Hills to sell the blue box ammunition at a
reduced price compared to their red box ammunition.





Black Hills’
75 grain Match HP (hollow point) ammunition is loaded with Hornady’s 75
grain BTHP Match bullet with a cannelure (referred to as the "T1C" here
on AR15.com) and both the red box and blue box loads have a crimp at
the case mouth. Both loads are charged with “ball powder.” The nominal
OAL for the red box cartridges ran around 2.245” and for the blue box
cartridges it was closer to 2.250".




The
cases used in the red box ammo have sealed primers and the headstamp of
most lots of this load read “BHA 223 MATCH.” These virgin cases have a
nominal length of 1.755”. The cases used in the blue box load tend to
be a mix of once fired Lake City and Winchester brass. The military
primer crimps has been removed by the reaming method. The blue box
loads do not have sealed primers.


Black
Hills does not perform a “trim to length” operation on the resized
cases used in the blue box ammunition. As a result, many of the cases
are longer than the SAAMI recommended maximum length of 1.760”. Several
of the cases that I measured had a length of 1.775”. This could
potentially cause problems in a barrel with a minimum length chamber,
though no malfunctions of any kind were experienced during the testing
of this ammunition. (Using a Sinclair chamber length gauge, I
determined the chambers of my Colt barrels have a length of 1.780”.)





Both
loads were chronographed using four different length barrels. All of
the Colt barrels used in testing have a NATO chamber and a 1:7” twist.
The 24” Krieger barrel has a 5.56 Match chamber and has a twist rate of
1:7.7”. On their web-site, Black Hills advertises a muzzle velocity of
2,750 fps for these loads, but they do not state the barrel length
associated with this velocity.





An Oehler 35-P chronograph with
“proof screen technology” was used in testing. All velocities listed
are muzzle velocities obtained from the instrumental velocities using
Oehler’s Ballistic Explorer software.  Strings of fire consisted of 10 rounds each.

While
chronographing the Black Hills loads through the 24” Krieger barrel, I
also chronographed three of Hornady’s SAAMI pressure, 75 grain loads
that use the T1C bullet for comparison.

Coming soon:  100 yard accuracy comparison.
atmospheric conditions:





Average temperature- 80 degrees F


Humidity - 48%


Barometric pressure – 29.04


Elevation- 960 feet above sea level
 





For additional comparison, I also fired the Black Hills loads
side-by-side with some of the Hornady 75 grain SAAMI pressure loads
from the 20” Colt A2 barrel.

 100 yard Accuracy Evaluation of Black Hills 75 grain MHP:  red box versus blue box.





As
previously discussed in this thread, the primary difference between
Black Hills' red box and blue box ammunition lies with the brass case.
Red box ammunition uses virgin brass, while blue box ammunition uses
once fired brass that has been resized.



Both the red box and
blue box 75 grain Match hollow point loads use the Hornady 75 grain
BTHP bullet with a cannelure and both have crimped case necks. Both
loads are charged with “ball” powder and with the two lots of this
ammunition that I chronographed the blue box load ran an average of 50
fps faster than the red box.



Accuracy testing of both loads was
done from a bench-rest at 100 yards. The test-vehicle was an AR-15 with
a 24” stainless-steel Kreiger VarMatch barrel, with a 1:7.7” twist,
installed on a LaRue Tactical Stealth upper receiver. A Leupold
Competition Series Scope was used for sighting. No malfunctions of any
kind were experienced during testing.

Prior
to testing the Black Hills ammunition, I obtained three 10-shot groups
of a control load consisting of hand-loaded Sierra 55 grain BlitzKings
(at a distance of 100 yards of course.) Those three groups had extreme
spreads of:



0.537”

0.57”

0.69”



for an average extreme spread of 0.599”.



The three 10-shot groups were overlayed on each using RSI Shooting Lab to obtain a 30-shot composite group that had a mean radius of 0.19”.
Best 10-shot group of the control load.





Following
the same procedures used with the control load, three 10-shot groups of
the Black Hills red box 75 grain MHP fired from 100 yards were
obtained. Their extreme spreads measured:



0.96”

1.00”

1.04”



for an average extreme spread of 1.00”.



As
with the control load, the three 10-shot groups from the red box
ammunition were overlayed on each other to obtain a 30-shot composite
group with a mean radius of 0.32”.



In
the same manner as above, three 10-shot groups of the blue box 75 grain
MHP were obtained from 100 yards with extreme spreads of:



1.11”

1.16”

1.16”



for an average extreme spread of 1.14”.



Those three 10-shot groups overlayed on each other had a mean radius of 0.37”.   Here are the 30-shot composite groups side-by-side for comparison.

The best 10-shot groups from the Black Hills 75 grain MHP loads.





Lastly,
for the Internet Commandos in our audience, I fired a 3-shot group of
the red box 75 grain MHP from 100 yards. That group measured 0.276”.






Here’s a repost of some of the chronograph data for the Black Hills loads.





 



 

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.
100 Yard Accuracy Evaluation of Prvi Partizan 75 grain Match Ammunition.







The Prvi Partizan 75 grain match ammunition uses an open-tip-match
bullet very similar in configuration to Hornady’s 75 grain BTHP bullet
used in Hornady’s TAP line of ammunition and in Black Hills’ 75 grain
MHP line of ammunition. The Prvi Partizan (PPU) bullet has a nominal
length that runs approximately 0.010” – 0.015” shorter than the Hornady
bullet. The PPU 75 grain bullet does not have a cannelure, but the case
mouth on this load does have a slight collet crimp on it which puts a
slight crease in the bullet.


The PPU 75 grain match load uses Boxer primed brass cases and is
charged with “ball” powder. Neither the primer nor the case mouth have
sealant and the primer is not crimped. Previous chronographing of this
load through multiple barrel lengths shows it to run an average of 127
fps slower than the Black Hills 75 grain MHP load.



I have read some statements recently that claim the PPU 75 grain
bullet was designed to shoot well through 1:9” twist barrels, yet none
of those making these statements have provided any scientific evidence
to support this claim. According to the Greenhill formula, the optimal
twist for the PPU 75 grain bullet is 1:7.6”.




From a 1:9” twist barrel, the PPU 75 grain match bullet has a
gyroscopic stability factor (GSF) of less than 1.25 for all velocities.
It is generally accepted that a rifle bullet should have a GSF of 1.5
to 2, with 1.25 being the least acceptable GSF.
Gyroscopc stability factor from a 1:9" twist barrel.







Gyroscopic stability factor from a 1:7.7" twist barrel.







The test-vehicle for this evaluation was an AR-15 with a 24”
stainless-steel Kreiger VarMatch barrel, with a 1:7.7” twist, installed
on a LaRue Tactical Stealth upper receiver. A Leupold Competition
Series Scope was used for sighting. No malfunctions of any kind were
experienced during testing.

Following my usual protocol for accuracy evaluation, shooting was
done from a bench-rest at 100 yards. Three 10-shot groups were obtained
using the PPU 75 grain match load. Those three groups had extreme
spreads that measured:





0.66”


0.92”


1.14”





for an average extreme spread of 0.91”.
The best 10-shot group from 100 yards.







The three groups from above were overlayd on each other using RSI Shooting Lab
to obtain a 30-shot composite group. The mean radius of this composite
group was 0.29”. For comparison, this composite group is pictured below
next to a composite group of the Black Hills 75 grain red box MHP load
as well as a composite group of one of my handloads.

Chronograph Data for Prvi Partizan 75 grain Match Ammunition

Chronograph data was obtained using an Oehler 35-P with "proof screen" technology.  All velocities listed are muzzle velocities as calculated from instrumental velocities using Oehler's Ballistic Explorer.  All strings of fire consisted of 10 shots each.





Three different barrel lengths were used in testing: 20", 16" and
14.5". All barrels were of Colt manufacture, with chrome lining, NATO
chambers and 1:7" twists.

atmospheric conditions:





Average temperature- 83 degrees F


Humidity - 64%


Barometric pressure – 30.04


Elevation- 960 feet above sea level
Prvi Partizan 75 grain Match; Velocity Update
Here's a little update on the velocity aspect of the PPU 75 grain
Match load. One can't help but wonder if Prvi Partizan has been
listening to its customers. About the only complaint anyone has had
with this load is that it has a lower muzzle velocity than the Hornady
or Black Hills 75 grain loads. I recently chronographed the latest lot
of the PPU 75 grain Match load that I have on hand and from a 20" Colt
A2 barrel it is running approximately 117 fps faster than the original
lots of this ammo that I chronographed!

 

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.





Wolf 75 grain HP





As
I’m sure you all know, Wolf is now distributing a 223 Remington, 75
grain hollow point version of their metal cased, “bi-metal” jacketed
bullet ammunition. While the 75 grain bullet does indeed have an open
tip at the meplat, it is not exactly a typical hollow point design as
the base of the bullet is also open, with exposed lead, as in the
configuration of a full metal jacketed bullet.

While
I’m sure you’ll bring up exceptions to my next statement, the odds are,
that if you are using 223 Remington Wolf metal cased ammunition, you’ll
probably be firing it from a chrome lined, NATO chambered barrel. For
this reason I chose to evaluate the accuracy of the Wolf ammunition
using just such a barrel. Accuracy testing was performed at a distance
of 100 yards shooting from a concrete bench. The free-float tube of the
rifle rode in a Sinclair Windage Bench Rest and the stock of the rifle
was stabilized in a Protecktor bunny-ear bag. Wind conditions were
continuously monitored using a Wind Probe.



The barrel used as
the test vehicle was a 20” Colt HBAR with a 1:7” twist and as mentioned
has chrome lining and a NATO chamber. This barrel has repeatedly
demonstrated the ability to fire 10-shot groups from 100 yards that
hover just above 1 MOA in extreme spread when using match grade
ammunition. Sighting was performed using a Leupold VARI-X III with a
mirage shade attached. Magnification was set to 25X and the scope was
adjusted to be parallax free at 100 yards.

Immediately
prior to testing the 75 grain Wolf ammunition, I fired a 10-shot
control group from 100 yards with the above set-up using factory loaded
Hornady 223 Remington 75 grain TAP ammunition. That 10-shot group had
an extreme spread of 1.1”.







In
order to remove as much of the human variable from the process as is
reasonably possible and to give the Wolf ammunition ample opportunity
to prove itself, I fired five, 10-shot groups of the Wolf ammunition
from 100 yards and used the smallest three of those groups for
evaluation. Those three groups had extreme spreads of:



5.5”

4.5”

5.7”



for an average extreme spread of 5.2”  The three groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group which had a mean radius of 1.47”.  



For
comparison, three 10-shot groups of Hornady’s steel cased 75 grain
“practice” ammunition previously fired from this same barrel at 100
yards had an average extreme spread of 1.45”.  The three 10-shot groups of the Hornady practice ammunition over-layed on each other to form a 30-shot composite group had a mean radius of 0.49”.

Here's a pic of the smallest Wolf 75 grain HP group.





At
one point during firing, I experienced a stoppage. Locking the bolt
back to examine the chamber area, I discovered a fired case stuck in
the chamber and observed that the extractor had torn throuh the case
head. The case had to be tapped out of the chamber using a cleaning rod
inserted from the muzzle. This is the only time that I have ever had a
case stick in the chamber of any of my AR-15s.

 

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.





Silver State Armory 77 grain OTM










Silver
State Armory is now producing a 5.56mm NATO pressure, 77 grain OTM load
with velocities on par with the Black Hills MK262 load. This makes SSA
the fourth commercial ammunition manufacturer to currently offer a
5.56mm heavy OTM round loaded to NATO pressure; the other three being
Black Hills (MK262), Hornady (5.56 TAP) and HSM (5.56-17T).



The
SSA 77 grain load comes in simple brown boxes with nothing more than a
“5.56” designation on it to give you a clue as to what’s inside the
box. There is no indication of the bullet weight found anywhere on the
box. This round is loaded with a 77 grain Sierra MatchKing without a
cannelure.





The
cartridge is charged with ball powder. The primers are crimped in
place, although some of the crimps are so shallow that I needed
magnification to see them. The primers are not sealed. As mentioned,
the bullet does not have a cannelure, but there does appear to be a
slight taper crimp on the case mouth that leaves a small indentation on
the bullet. There is no sealant at the case mouth.









The
SSA 77 grain load was chronographed using an Oehler 35-P chronograph
with “proof screen” technology. All velocities listed are muzzle velocities, as calculated from instrumental velocities using Oehler’s Ballistic Explorer
software program. All strings of fire consisted of 10 shots each. Colt
barrels in the lengths of 20”, 16” and 14.5’ were used as the test
vehicles. All barrels used were chrome lined, NATO chambered and have
1:7” twists. Atmospheric conditions were recorded using a Kestrel 4000.





Temperature: 74 degrees F

Humidity:  58%

Barometric pressure:30.15 in Hg

Elevation: 950 feet above sea level



The
SSA 77 grain cartridges had a nominal length of approximately 2.250”.
All rounds used in this test session fed, fired, extracted and ejected
without any malfunctions. There was definite primer flattening noted on
the fired caseheads, but no significant ejector or extractor brass flow
marks.

Finally, here’s the data!







At
one point during the test session I noticed an unexpected visitor on
the range. The big guy pictured below was sitting on the berm about 10
feet above the target frame watching me.







Accuracy Report





Following
my usual procedures, an accuracy evaluation of the Silver State Armory
77 grain OTM NATO load was conducted shooting from a concrete bench at
a distance of 100 yards. The test vehicle used for this evaluation was
a Noveske barreled RECCE. The 16” Noveske Recon barrel is made of
stainless steel and has the 5.56 Noveske Match Mod 0 chamber, a 1:7"
twist and polygonal rifling. The barrel is free-floated in a LaRue
Tactical railed handguard.


The
fore-end of the RECCE was rested in a Sinclair Windage Bench Rest with
the aid of a modified Sinclair fore-end stabilizer. The butt-stock was
stabilized in a Protektor bunny-ear bag. Sighting was accomplished
using a Leupold VARI-X III with a mirage shade attached. Magnification
was set at 25X and the scope was adjusted to be parallax free at 100
yards. The lower receiver used during testing has a Geissele match
rifle trigger in it.


Atmospheric
conditions were recorded on a Kestrel 4000. Skies were sunny and the
winds were breezy. Wind conditions were continuously monitored using a
Wind Probe which was positioned approximately 33 yards from the muzzle.





Temperature:  77 degrees F

Humidity:  51%

Barometric pressure:  29.87 inHg

Elevation: 950 feet above sea level


Prior
to firing the SSA 77 grain load, I fired a 10-shot control group from
100 yards using a hot hand-load seated with Sierra 77 grain MatchKings
(the same bullet used in the SSA load). That group had an extreme
spread of 0.97”.

Three
10-shot groups of the SSA 77 grain OTM NATO load were fired from 100
yards using the described set-up. Those groups had extreme spreads of:



1.92”

1.60”

2.03”



for an average extreme spread of 1.85”.  Those three groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius of the composite group was 0.54”.



For
comparison, three 10-shot groups of Hornady’s 75 grain 5.56 TAP
previously fired from the same Noveske barrel had extreme spreads of:



1.03”

1.42”

1.20”



for
an average extreme spread of 1.22”. The 30-shot composite group formed
by over-laying those three groups on each other had a mean radius of
0.37”. The composite groups of the two different loads are shown below
for visual comparison.

Lastly,
for the Internet Commandos in our viewing audience I fired a 3-shot
group of the SSA 77 grain load from 100 yards. That group had an
extreme spread of 0.80”.







 

All credit review for this post belongs to MOLON. I merely pasted his review in this post with his permission - Z.
Hornady 5.56 TAP versus TAP FPD
For those interested in Hornady's 75 grain TAP loads, here are the
results of a side by side chronograph test of Hornady’s 75 grain 5.56
TAP round (NATO pressure) and their SAAMI pressure 75 grain TAP FPD
(For Personal Defense) round. The TAP FPD comes in a “black box” and
uses “black nickel” plated cases. The TAP 5.56 comes in a “red box” and
has brass cases with crimped primers and uses the new “T2” 75 grain
bullet. Both bullets have a cannelure and both rounds have a crimped
case neck.
The ammunition.


The cartridges.

The headstamps.  Note the 5.56 round has a crimped in primer.

The 5.56 TAP uses ball powder...

...and the TAP FPD uses a short cut extruded powder.

The bullet on the left is a virgin 75 grain BTHP sold as a
reloading component. The bullet in the center is pulled from a TAP FPD
round and the bullet on the right is the new “T2” bullet pulled from a
round of the 5.56 TAP.

The tests were conducted using an Oehler 35P chronograph with
"proof screen" technology. All strings of fire for this report
consisted of 10 rounds each unless otherwise noted. All of the
velocities listed in this report are MUZZLE velocities and were calculated from the instrumental velocities using Oehler’s Ballistic Explorer software.  The ballistic coefficients used for this study are estimates
extrapolated from Hornady’s exterior ballistics tables for these two
loads. If anyone has more precise ballistic coefficients for these
loads please feel free to post them.






The three different barrels used in testing were:
A Colt 14.5” M4 barrel



A Colt 16” light weight profile barrel



A Colt 20” government profile barrel
All of the barrels used are chrome lined, NATO chambered and have 1:7” twists.

Here is a table showing the muzzle velocities of each load from
each of the three different barrels, along with a column showing the
difference in velocities between the two loads.

If you read the fine-print in the above table you'll notice that
the results for the 20” barrel were obtained using 20-shot strings of
fire. This was part of a test to determine the validity of using
10-shot strings of fire when chronographing. I fired a 10-shot string
of each load using the 20” barrel and then a 20-shot string of each
load and compared the results. For the TAP FPD the difference in the
average velocity between the 10 and 20 shot strings was ONE foot per
second and the standard deviations were the same! With the 5.56 TAP the
difference in average velocities between the 10 and 20 shot strings was
only five fps and the standard deviations only varied by one foot per
second. I think this shows quite nicely the validity of using 10-shot
strings for chronographing.

The Hornady 75 grain bullets are considered to have a fragmentation
threshold of 2200 fps +/- 50 fps. Based on the conservative figure of
2250 fps the table below shows the range (in yards) at which
fragmentation can be expected to occur for the two loads being tested.
It also shows the gain (in yards) before reaching the fragmentation
threshold for the 5.56 TAP load.

On my next trip to the range I will be conducting an accuracy
comparison between these two loads. I’ll post those results as soon as
they are available.
For additional comparison, I chronographed a few other factory loads “of interest.”  Here are the results.

Lastly, for all the O.C.D. types, here are the atmospheric conditions during testing:
Temperature- 84 degrees F



Humidity - 53%



Barometric pressure – 30.02



Elevation- 960 feet above sea level



Winds – variable



Skies – partly cloudy, Jupiter aligned with Mars
 Here is the revised fragmentation range table using the ballisitic
coefficient of .352 for both the "T1" and "T2" bullets. The
fragmentation threshold of 2,250 fps is used with my original muzzle
velocities along with Standard Atmospheric Conditions.*

*Stand Atmospheric Conditions for ballistics.





Altitude: Sea level


Barometric pressure: 29.53 inches Hg


Temperature: 59 degrees F


Relative humidity: 78 percent



 





Accuracy Results - part 1
Normally
when attempting to determine the accuracy (technically the precision)
of a particular load, I use one of my stainless steel Krieger barrels
for testing. However, since part of this test involves the 5.56 TAP
round loaded to NATO pressures, I was just not willing to risk pressure
issues from firing a NATO pressure load through one of my match
chambered, tightly rifled Krieger barrels.





I could have used a
Krieger barrel for the SAMMI pressure 75 TAP FPD load and a different
barrel for the 5.56 TAP load, but I felt this would have given an
unfair advantage to the TAP FPD. Therefore I decided to test both loads
from a NATO chambered barrel. What I was most interested in gleaning
from this test was the relative
accuracy of the two loads compared to each other anyway. It has been my
experience that NATO pressure loads tend not to shoot as accurately as
loads that are downloaded by 150 to 200 fps (depending on the bullet
weight.)


 


I have a 20” Colt HBAR with a 1:7” twist that shoots
relatively well for a factory barrel that is chrome lined and NATO
chambered. The barrel is free floated and is capable of shooting
10-shot groups from 100 yards that hover right around one inch.

All
shooting for this test was done at 100 yards from a benchrest with the
rifle resting on front and rear bags. (Remember, I’m trying to test the
accuracy of the ammunition and not particularly my shooting skills.) As
a control for this test, before firing the TAP ammunition, I obtained
three 10-shot groups using Sierra 77 grain MatchKings. (In an effort to
reduce the human error involved in this test, I actually fired four
10-shot groups of each load and used the best three for analysis.)





The three 10-shot groups using the Sierra 77 grain MatchKings measured:





1.05”


1.07”


1.10”.





Here is a snapshot of one of the 77 SMK groups.





Now here’s the good part.  I obtained three 10-shot groups of the Hornday 75 grain TAP FPD load and the three groups measured:





1.08”


1.15”


1.18”.





Here is a snapshot of one of the 75 TAP FPD loads.





Next I overlayed the three 10-shot groups from each load on each other using the RSI Shooting Lab
software program and obtained 30-round composite targets for each load.
The mean radius of the 77 SMK control load measured 0.32” and the mean
radius for the 75 TAP FPD load measured 0.37”! I consider this to be
excellent accuracy for a factory load, especially from a chrome lined,
NATO chambered barrel.





(See this thread for an explanation of the “mean radius.”)





Here are the 30-round composite targets for comparison.










Tomorrow I will be testing the 5.56 TAP load and I’ll post the results as soon as I get a chance.






 





Accuracy Results – part 2





Proceeding
in the same manner as described in part 1, I conducted an accuracy
evaluation of the 5.56 TAP load. Remember, all groups fired consisted
of 10 shots each and were fired from 100 yards from a bench rest.





For
this portion of the test, I fired a 10-shot group using the control
load with the Sierra 77 grain MatchKing that measured exactly 1.00”.
This is the smallest group obtained with the control load, with the
largest being 1.10”. This group along with the three groups fired in
part 1 of this test gives us four 10-shot groups of the control load
fired from 100 yards that have an extreme variance of only 1/10th
of an inch! (1.00”, 1.05”, 1.07”, 1.10”) I think this gives a pretty
good indication of the capabilities/limitations of the barrel being
used for testing and did not think that any more control groups were
necessary.





Here’s a snapshot of the control load.





Now for the really good part.  I obtained three 10-shot groups of the 5.56 TAP load that measured:





1.16”


1.38”


1.45”.





For comparison the three 10-shot groups of the TAP FPD load from part 1 of the test measured:





1.08”


1.15”


1.18”.





Here is a snapshot of the smallest 5.56 TAP group.










I
compiled a 30-round composite target from the 5.56 TAP groups and
measured the composite mean radius. The mean radius for the 5.56 TAP
load was 0.46" while the mean radius for the TAP FPD load was 0.37".
While the 5.56 TAP load is clearly not quite as accurate as the TAP FPD
load (and we are only talking about a difference of 0.37” from the
smallest FPD group to the largest 5.56 group at 100 yards in this
test), I think the 5.56 load shows excellent accuracy for a NATO
pressure load. As I stated earlier, it has been my experience that NATO
pressure loads do not shoot nearly as accurately as loads that run
150-200 fps slower.





Here are the 30-round composite targets for comparison.










For my next trip to the range I am thinking of conducting a "stability test" for the TAP loads.
 
Stability Test – final results



After
testing the TAP loads at 50 yards for signs of instability I continued
the testing from 100 yards. As stated in the preliminary results post,
this test uses a Colt 16” HBAR with a 1:9” twist and is chrome lined
and NATO chambered.



Before getting to the results I’d like to mention a couple of points as suggested by wyv3rn.
First of all, not all 1:9” twist barrels are exactly one turn in nine
inches. Some might be slightly faster, such as a 1:8.8” twist and some
might be slightly slower, such as a 1:9.2” twist. The point being that
your 1:9” twist barrel might be a little different than mine and
therefore your stability results may also differ from mine. Secondly,
rotational stability is influenced by ambient temperature. A round that
is stable on a nice sunny summer day might not be so in the middle of
winter.

 

On to the test results. Before firing the TAP rounds,
I obtained a 10-shot control group using Sierra 52 grain MatchKing
bullets. The group measured 1.01” and had a mean radius of 0.36”. This
group is a fine example of the accuracy this barrel is capable of as I
have duplicated these results numerous times in the past with this
barrel.



Here is a pic of the control group.








First
up for the TAP loads was the TAP FPD load. You may recall this load
showed excellent accuracy when fired from a 1:7” twist barrel. Using
the Colt 16” barrel with the 1:9” twist I obtained three 10-shot groups
from 100 yards that measured:



1.28”

1.65”

1.76”.



For comparison the three 10-shot groups of the TAP FPD load fired from the 1:7” twist barrel measured:



1.08”

1.15”

1.18”.



Using my usual procedure of overlaying three 10-shot groups on each other using RSI Shooting Lab
software I obtained a 30-round composite target of the rounds fired
from the 1:9” twist barrel. The mean radius for this target was 0.48”.
By comparison, the mean radius of the 30-round composite target for the
TAP FPD load fired from the 1:7” twist barrel was only 0.37”. This
shows a definite increase in group size for the rounds fired from the
1:9" twist barrel.












Next,
following the same procedures, I obtained three 10-shot groups of the
5.56 TAP load through the 1:9” twist barrel that measured:



1.44”

1.90”

2.06”.



For comparison the three 10-shot groups obtained from the 1:7” twist barrel measured:



1.16”

1.38”

1.45”.



As
before, 30-round composite targets were compiled to compare the mean
radii. The mean radius from the 1:9” twist barrel measured 0.54” while
the mean radius from the 1:7” twist barrel measured 0.46”. Again we see
an increase in group size for the rounds fired from the 1:9” twist
barrel. (Keep in mind that the control group from the 1:9” twist barrel
was right on par with the control groups from the 1:7” twist barrel.)










All
the bullet holes from both TAP loads were typically rounded bullet
holes. There was no sign of key-holing whatsoever. However, with both
the TAP FPD and the 5.56 TAP we are seeing an obvious increase in group
size when fired from the 1:9” twist barrel (although in practical terms
the increase in group size is less than one inch from the smallest TAP
FPD group fired from the 1:7" twist barrel to the largest 5.56 TAP
group fired from the 1:9" barrel at 100 yards.)



Obviously, test results from just one barrel with a 1:9” twist don’t prove anything and it could be that my barrel just doesn’t like the 75 grain bullets.  However, I think the results suggest
that the TAP rounds were only marginally stabilized in the 1:9” twist
barrel under the ambient conditions and that is the reason for the
decrease in accuracy compared to the 1:7” twist barrel. Feel free to
post your conclusions.





Atmospheric conditions:



Temperature:  76 degrees F

Relative humidity: 39%

Barometer:  30.19

Elevation:  960 feet above sea level
 



 

Recent ballistic gelatin testing of popular rounds:

223 Privi Partizan 75 gr OTM, velocity=2468 fps from a 16" barrel:

Penetration in bare gel  Neck Length        Max temporary cavity         Recovered Diameter  Recovered Length  Recovered Weight   %fragmnentation

         12.6"             2cm        diameter = 8cm @ 12cm from 2-20cm        0.36"               0.15"           30.1gr                60%

5.56 mm Hornady 75 gr T2 TAP OTM, velocity=2689 fps from a 16" barrel:

Penetration in bare gel  Neck Length        Max temporary cavity         Recovered Diameter  Recovered Length  Recovered Weight   %fragmnentation

         13.8"             2cm        diameter = 11cm @ 12cm from2-23cm        0.40"               0.25"           30.5gr                59%

5.56 mm BH 77 gr Mk262 Mod1 OTM (SMK), vel=2700 fps from a 16" barrel

Penetration in bare gel  Neck Length        Max temporary cavity         Recovered Diameter  Recovered Length  Recovered Weight   %fragmnentation

         15.8"             7cm        diameter = 11cm @ 15cm from 7-25cm        0.42"               0.12"           25.7gr                66%

DocGKR's comments: "The Hornady 75 gr was the most impressive loading in bare gel––evenmore so than the numbers illustrate and it was extremely consistent..."

ALL DATA IN THIS POST BELONGS TO MOLON. I am merely re-posting it in this review thread to save him the time and effort.





Nosler 77 grain BTHP












In 2003, Nosler introduced their 77 grain Custom Competition BTHP
bullet as an obvious competitor to the 77 grain Sierra MatchKing. The
shape and ballistic coefficient of the Nosler bullet is very similar to
that of the Sierra MatchKing. The Nosler bullet does have one major
difference from the Sierra MatchKing; it is constructed using the
thinner J4 copper jacket.





I recall an early Nosler advertisement for their Custom Competition
bullet that included a phrase saying the bullet was “ideal for military
and law enforcement,” hinting at the possibilities of improved
fragmentation due to the thinner J4 jacket. Thanks to the works of Dr.
G.K. Roberts and B&T Ammo Labs, we know that the 77 grain Nosler
bullet loaded to mil-spec velocities has superior terminal ballistic
properties to that of the 77 grain Sierra MatchKing loaded in MK262.
The terminal ballistic properties of the 77 grain Nosler bullet loaded
to mil-spec velocities rival that of the Hornady 75 grain 5.56 TAP
load. Unfortunately, there are no ammunition manufacturers currently
loading the 77 grain Nosler to mil-spec velocities.









Courtesy of Dr. G.K. Roberts



Courtesy of B&T Ammo Labs
The Nosler 77 grain Custom Competion bullet is typically sold
without a cannelure, however Nosler occasionally releases the bullet
with a shallow cannelure similar to the one found on the 77 grain SMK
loaded in MK262. The cannelured version of the 77 grain Nosler will be
the focus of this report.



For the first phase of testing, I hand-loaded the cannelured
version of the 77 grain Nosler BTHP to a typical SAAMI velocity
(approximately 2600 fps from a 20” Colt barrel) to establish an
accuracy baseline. No case mouth crimp was applied at this phase. As
per my usual protocol, accuracy testing was conducted from a concrete
benchrest at a distance of 100 yards. The forend of my Krieger barreled
AR-15 rested in a Sinclair Windage Benchrest, while the stock of the
rifle rode in a Protektor bunny-ear rear bag. A Leupold Competition
Scope was used for sighting. Wind conditions were monitored using a
Wind Probe.

Three 10-shot groups were obtained which had extreme spreads of:





0.797”


0.827”


0.812”





for a 10-shot group average of 0.812”.  The three groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group.  The composite group had a mean radius of 0.26”.
This test shows that the Nosler bullet itself is capable of consistent
sub-MOA accuracy at 100 yards when fired from a semi-automatic AR-15.







For the second phase of testing, I safely worked up a load for the
77 grain Nosler BTHP to a nominal muzzle velocity of 2800 fps from a
20” barrel using a non-canister grade military powder which has a
velocity-to-powder-charge ratio that is very close to that of the
powder used in MK262. (In previous testing, I found that the average
muzzle velocity from seven different lots of Hornady 5.56 TAP was 2808
fps from a 20” barrel.) No case mouth crimp was used in this phase of
testing either.





Since my Krieger barreled AR-15 has a 5.56mm Match chamber that is
“a little too tight” for mil-spec pressure loads, I used my AR-15 with
a 20” Noveske DCM barrel for this phase of testing. This Noveske barrel
has the “Noveske Match Mod 0 chamber which is designed to offer 100%
reliability while retaining maximum possible accuracy. The chamber body
is slightly larger than the 5.56mm NATO minimum, but within the 5.56
NATO tolerance. The throat is redesigned for proper bullet alignment
with the axis of the bore. This chamber was developed to fire MK262 Mod
1 on AUTO in hot environments."












Accuracy testing using the Noveske barreled AR-15 and Nosler 77
grain BTHP at a muzzle velocity of 2800 fps was conducted in the same
manner as described above in the first phase of testing. Three 10-shot
groups were obtained from 100 yards. Those groups had extreme spreads
of:





0.880”


0.857”


0.845”





for a 10-shot group average of 0.860”.
These groups were over-layed on each other using RSI Shooting Lab to
form a 30-shot composite group which had a mean radius of 0.29”.







For the final phase of testing I added a taper crimp to the case
mouth of the previously described load used in phase two. A 10-shot
string of this load fired over the Oehler 35-P chronograph from my 20”
Novekse barrel had a muzzle velocity of 2801 fps with a standard
deviation of 12 fps.





Three 10-shot groups fired from 100 yards from the 20” Noveske DCM barrel had extreme spreads of:





1.033”


0.914”


1.241”





for a 10-shot group average of 1.063”.  As before, the three groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group.  The mean radius for the composite group was 0.31”.  

Previous accuracy testing of the 75 grain Hornady 5.56 TAP load
from my 16” Noveske barreled AR-15 produced a 10-shot group average of 1.22” at a distance of 100 yards with a 30-shot composite group mean radius of 0.37”.  





As previously mentioned the 77 grain Nosler BTHP has terminal
ballistic properties on par with the TAP load. This testing shows that
the 77grain Nosler BTHP bullet loaded to a muzzle velocity of 2800 fps,
is capable of accuracy that is slightly better than that of the TAP
load.


 

ALL CREDIT FOR THIS POST BELONGS TO MOLON - I AM MERELY REPOSTING IT IN THIS SECTION - Z.





MK318 Mod 0 (Federal T556TNB1)

The SOST projectile loaded in the MK318 Mod 0 cartridge has a
nominal weight of 62 grains and a nominal length of 0.87”.  It is
constructed with a copper base and a small, non-bonded lead core in the
ogive section of the bullet.  Due to this higher copper to lead ratio,
the MK318 Mod 0 projectile is longer than a traditional copper
jacketed/lead core projectile of the same weight, but is still slightly
shorter than an M855 projectile.


While it is often stated that the SOST projectile used in MK318 Mod 0
is similar to the Federal Trophy Bonded Bear Claw, the form of the SOST
projectile more closely resembles that of Federal’s Trophy Bonded Tip
projectile (without the tip of course.)  As previously mentioned, the
MK318 projectile does not have a bonded core.




The loaded MK318 Mod 0 cartridge has a nominal OAL of 2.20". The
projectile does not have a cannelure per se, but the case mouth is
crimped into the top relief band.  The cartridge is sealed at the case
mouth, however not with the asphalt sealant typically found on military
ammunition.  The primers are sealed and crimped.  The casehead is
stamped "FC 10".  The cartridge is charged with ball powder.


A typical copper jacketed/lead core FMJ bullet will have a specific
gravity of approximately 10.2.  Due to its higher copper to lead ratio
construction, the MK318 Mod 0 projectile has a lower specific gravity of
9.4.  When fired from  typical AR-15 barrel lengths with a 1:9” twist
rate, MK318 Mod 0 will have a gyroscopic stability factor of  
approximately 1.3.

When fired from typical length barrels with a 1:7" twist rate, MK318
Mod O will have a gyroscopic stability factor of approximately 2.2.

MK318 Mod 0 Chronograph Data





Chronographing of the Mk318 Mod 0 ammunition was conducted using an
Oehler 35-P chronograph with "proof screen” technology. All velocities
listed below are muzzle velocities as
calculated from the instrumental velocities using Oehler’s Ballistic Explorer software
program. All strings of fire consisted of 10 rounds each.








Each round was single-loaded and cycled into the chamber from a
magazine fitted with a single-load follower.  The bolt locked-back after
each shot allowing the chamber to cool in between each shot.  This
technique was used to mitigate the possible influence of "chamber-soak”
on velocity data. Each new shot was fired in a consistent manner after
hitting the bolt release.   Atmospheric conditions were monitored and
recorded using a Kestrel 4000 Pocket Weather Tracker.

Atmospheric conditions:





Temperature:  75 degrees F.


Humidity:  47%.


Barometric pressure: 29.97 inches of Hg


Elevation:  950 feet above sea level
Two different barrel lengths were used in obtaining velocity data; a
14.5” Colt M4A1 barrel and a 20” Colt M16A2 barrel.  Both barrels have
NATO chambers, are chrome lined and have 1:7” twist rates.  Both barrels
have low round-counts on them.  
M4A1 barrel.



M16A2 barrel.






For comparison, the MK318 Mod 0 ammunition was fired in sequence
with two different brands of 62 grain M855 ammunition.  The firing order
for both barrels was as follows:





1.A 10-shot string of Winchester Ranger M855


2.A 10-shot string of MK318 Mod 0


3.A 10-shot string of IMI M855





Finally, the data:


The Crane Warfare Centers' publication, "U.S. Navy Small Arms
Ammunition Advancements” reported that MK318 was "optimized” for the MK
16 with a 14 inch barrel and claimed it has a velocity of 2925 fps at 15
feet from the muzzle (presumably from said 14 inch barrel.) The lot of
Federal T556TNB1 (MK318 Mod 0) that I chronographed from the Colt 14.5”
M4A1 barrel would have a velocity of approximately 2889 fps at 15 feet
from the muzzle (at standard atmospheric conditions.)
Accuracy Evaluation of MK318 Mod 0





An accuracy (technically, precision) evaluation of the MK318 Mod 0
ammunition was performed following my usual protocol.  This accuracy
evaluation used statistically significant shot-group sizes and every
single shot in a fired group was included in the measurements. There was
absolutely no use of any Group Reduction Techniques (e.g. fliers,
target movement, Butterfly Shots).





The shooting set-up will be described in detail below. As many of
the significant variables as was practicable were controlled for. Also, a
 "control group" was fired from each barrel used in the evaluation
using match-grade, hand-loaded ammunition; in order to demonstrate the
capability of the barrel. Pictures of shot-groups are posted for
documentation.





All shooting was conducted from a concrete bench-rest from a
distance of 100 yards (confirmed with a laser rangefinder.) The barrels
used in the evaluation were free-floated. The free-float handguards of
the rifles rested in a Sinclair Windage Benchrest, while the stock of
the rifles rested in a Protektor bunny-ear rear bag. Sighting was
accomplished via a Leupold VARI-X III set at 25X magnification and
adjusted to be parallax-free at 100 yards. A mirage shade was attached
to the objective-bell of the scope. Wind conditions on the shooting
range were continuously monitored using a Wind Probe. The set-up was
very similar to that pictured below.






The Wind Probe.






In order to establish a working baseline for the intrinsic accuracy
of the 62 grain SOST projectile itself, when fired from a semi-automatic
AR-15, I worked-up a SAAMI pressure hand-load with pulled MK318 bullets
and fired a 10-shot group of that load from a Krieger barreled AR-15
from a distance of 100 yards.  The Krieger barrel has a 1:7.7” twist
rate.






Prior to firing the 62 grain SOST hand-load, I fired a 10-shot
control group consisting of hand-loaded 62 grain Berger hollow points.  
The extreme spread for the control group measured 0.66”.

The extreme spread of the 10-shot group of the 62 grain SOST
hand-load measured 1.9”.



Since MK318 Mod 0 is intended for use as a combat round, I used
AR-15s with chrome-lined, NATO chambered barrels for this accuracy
evaluation.  As previously mentioned, it is reported that MK318 was
"optimized” for a 14 inch barrel, so it seemed only fitting to evaluate
MK318 from a similar length barrel.  The first test vehicle used in this
accuracy evaluation was a 14.5” Colt M4A1 barrel.  The barrel was
free-floated with a Daniel Defense Omega rail.  (I was not able to use
the mirage-shade with this barrel, due to the original standard front
sight base on it.)  A previous accuracy evaluation of this M4A1 barrel
demonstrated that this barrel is capable of excellent accuracy for a
chrome-lined, NATO chambered barrel.  That evaluation can be viewed
here:





The Colt M4A1 SOCOM Barrel


A control group fired from the M4A1 barrel using hand-loaded 62
grain Berger hollow-point projectiles had an extreme spread of 1.13”.

Three 10-shot groups of the MK318 were fired from the Colt M4A1
barrel from the previously described bench-rest set-up.  The extreme
spreads of those groups measured:





2.91”


3.22”


2.70”





for a 10-shot group average extreme spread of 2.94”.  The three
10-shot groups were over-layed on each other using RSI Shooting Lab to
form a 30-shot composite group.  The mean radius of this composite group
was 1.02”.  (For those of you not familiar with the mean radius, I've posted an
explanation of it in the third post of this thread.)
The smallest 10-shot group of MK318 fired from the Colt M4A1 barrel
is shown below.

The next test vehicle was a 16” Colt HBAR with a 1:9” twist.  This
is the same barrel found on the Colt 6721 Tactical Carbine.  This barrel
is one of the most accurate "out of the box” chrome-lined, NATO
chambered barrels that I’ve evaluated.  The barrel was free-floated with
a LaRue Tactical handguard.  

A 10-shot group from this barrel fired using hand-loaded Sierra 52
grain MatchKings had an extreme spread of 0.98”.

Three 10-shot groups of the MK318 fired from the Colt 6721 barrel
produced the following extreme spreads:





2.98”


2.85”


2.89”





for a 10-shot group average extreme spread of 2.91”.  These three
groups were also over-layed on each other to produce a 30-shot composite
group with a mean radius of 0.82”.
The smallest 10-shot group of MK318 fired from the Colt 6721 barrel .
. .

The third barrel used to evaluate the accuracy of MK318 was a 20”
Colt HBAR with a 1:7” twist, chrome-lining and a NATO chamber.  The
barrel is free-floated with a PRI handguard.

A 10-shot group from this barrel fired using hand-loaded 55 grain
Sierra BlitzKings had an extreme spread of 1.18”.

Three 10-shot groups of the MK318 fired from the 20” HBAR had
extreme spreads of:





2.70”


2.49”


3.24”





for a 10-shot group average extreme spread of 2.81”.  As before, the
three 10-shot groups were over-layed on each other to form a 30-shot
composite group that produced a mean radius of 0.91”.
The smallest 10-shot group of MK318 fired from the 20” HBAR . . .

A summary of the results from this evaluation are shown below.

Lastly, for the Internet Commandos in our viewing audience, here’s a
pic of a sub-MOA group of the MK318 fired from the 16” Colt HBAR from
100 yards; a cherry-picked 3-shot
group that is.

continued in next post . . .
 

ALL CREDIT FOR THIS POST
BELONGS TO MOLON - I AM
MERELY REPOSTING IT IN THIS SECTION - Z.




MK318 Mod 0 is also available to the general public in a "brown box”
version.  This version is labeled with the Department of Defense
Identification Code of AB49.
- V
e l o c i t y  -  C o m p a r i s o n -
Following the same chronographing procedures outlined in the first
post of this thread, I compared the velocities of T556TNB1 "white box”
MK318, to that of AB49 "brown box” MK318.  The two versions were fired
"back to back” from three different barrel lengths:





  14.5” Colt M4A1 (the same barrel used for the first post)





  16” Colt light-weight barrel, 6520





  20” Colt M16A2 (a different barrel than the one used for the
first post).
All three barrels are chrome-lined and have NATO chambers and 1:7”
twist rates.  The velocities listed below are muzzle velocities as
calculated from the instrumental velocities using Oehler’s Ballistic Explorer.
Atmospheric conditions.





Temperature:  72 degrees F


Humidity:  68.1%


Barometric pressure:  30.02 inches of Hg


Elevation:  950 feet above sea level

- A
c c u r a c y  -  C o m p a r i s o n -
Using the same 20” Colt HBAR, described in the original accuracy
evaluation in this thread, as the test vehicle, I performed an accuracy
evaluation of the AB49 "brown box” MK318 ammunition.  The evaluation was
conducted from a bench-rest at 100 yards in the same manner as
previously described.

Prior to firing the AB49 ammunition, a 10-shot control group of
hand-loaded, match-grade 55 grain Sierra BlitzKings was fired from 100
yards.  That group had an extreme spread of 1.00”.

Three 10-shot groups of the AB49 fired from 100 yards had extreme
spreads of:





3.26”


3.42”


3.31”





for a 10-shot group average extreme spread of 3.33”.  The mean
radius for the 30-shot composite group was 0.98”.  The accuracy results
are summarized and compared to those of T556TNB1 below.

The smallest 10-shot group of AB49.