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Posted: 5/29/2006 1:28:56 PM EDT
[Last Edit: Molon]
Hornady 5.56 TAP T2 versus TAP FPD


For this article I compared Hornady’s 75 grain 5.56mm  TAP T2 round  to their 223 Remington 75 grain TAP FPD (For Personal Defense) round.  The TAP FPD comes in a “black box” and uses “black nickel” plated cases.  The TAP 5.56mm 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 5.56mm TAP uses "temperature stablized" 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 5.56mm TAP T2.  

I asked Dave Emary (Chief Ballistician for Hornady) about the redesign of the ogive on the T2 bullet.  Here was his reply:

“We made the ogive radius shorter, makes the ogive a little fatter, on the TAP load because testing showed it fed better in the M16/AR."









5.56mm T2













While the original 5.56 TAP was loaded in “Frontier” head-stamped cases, the load now comes in "Hornady" head-stamped brass.





In interim years, the 5.56 TAP T2 has also been seen loaded in Lake City and Winchester cases.












The original lots of 5.56 TAP did not have sealed primers.  When Hornady did started sealing the primers, it was reported that this sealant was a new “anaerobic” type.  It had a distinctly “rubbery” feel to it as compared to traditional lacquer type sealants.  











The primer sealant used in one of the later lots of  5.56 TAP that I've tested appears to have a different consistency than the original sealant used.











Contrary to internet myths and even Hornady promotional material, for years after its introduction, 5.56 TAP did not have sealed case mouths.  Sealant at the case mouth on 5.56 TAP has been a relatively recent development.  I first noticed it with lot #3071004 and oddly, I've noticed some lots after that one that didn't have the case mouth sealant; go figure.











.....






Since its introduction, Hornady TAP FPD ammunition has been loaded in black-nickel coated cases.  According to Hornady these “revolutionary” cases “eliminate the potential for corrosion and improve feeding in all firearms.”

In 2009, Hornady began loading the TAP FPD ammunition in “revolutionary” silver-nickel coated cases and according to Hornady these cases “eliminate the potential for corrosion and improve feeding in all firearms.”  Hornady also states that these newest cases “are easier to see in low-light conditions and when checking for loaded chambers.”





.....

Velocity


Chronographing was 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 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.



Attachment Attached File




Atmospheric Conditions

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



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.








VelocityUpdate


Velocities of the various 5.56 TAP lots have remained remarkably consistent over the years.  I still had a few boxes of each lot of 5.56 TAP that I had tested over the last 2½ years, so I decided to fire 10 rounds from each lot over a chronograph in back-to-back fashion.  Seven different lots were tested using an Oehler 35-P chronograph with “proof screen” technology.  The rounds were fired from a 20” Colt M16A2 government profile barrel with chrome lining, a NATO chamber and a 1:7” twist.  All velocities listed below are muzzle velocities, as calculated from the instrumental velocities using Oehler’s Ballistic Explorer.  None of the lots tested had an average muzzle velocity that varied more than 0.61% from the grand average muzzle velocity of 2808 fps and most of the lots varied significantly less than that.








....




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.  

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

1.05”
1.07”
1.10”.



(In an effort to reduce the human error involved in this test, I actually fired four 10-shot groups of each factory load and used the best three for analysis.)





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”.



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.”)

....


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.


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”.



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.



......


5.56 TAP T2 Terminal Ballistic Test Results


Testing by DocGKR shows that Hornady's 75 grain 5.56mm TAP T2 load continues to have some of the best terminal ballistic properties of any non-barrier blind 5.56mm/223 Remington load currently available.  Here's a quote from Dr. Roberts on the Hornady load: "The Hornady 75 gr was the most impressive loading in bare gel––even more so than the numbers illustrate and it was extremely consistent..."


Hornady 5.56 mm 75 grain T2 TAP OTM

Velocity:  2689 fps from a 16" 1:7” twist barrel

penetration in bare ballistic gel: 13.8"

neck length: 0.8”

Maximum temporary cavity:  4.3” at a depth of 4.7”

Recovered diameter:  0.40”

Recovered length: 0.25”

Recovered weight: 30.5gr

Percentage of fragmentation:  59%




...........
...........




Link Posted: 5/29/2006 2:01:48 PM EDT
[#1]

Excellent work, Thanks for the data.

Link Posted: 5/29/2006 2:02:09 PM EDT
[#2]
Well informative, You did a exellent job comparing.
Link Posted: 5/29/2006 2:16:18 PM EDT
[#3]
Thanks for the info!  Excellent work, BTW!
Link Posted: 5/29/2006 4:16:22 PM EDT
[#4]
Link Posted: 5/29/2006 4:32:54 PM EDT
[#5]

Originally Posted By Troy:
That's a first-class comparison.  smiley.onegreatguy.net/thumbup.gif

-Troy


+1!
Link Posted: 5/29/2006 5:22:39 PM EDT
[Last Edit: SOSNBA] [#6]
All good information that correlates fairly well with my testing in 20" and 16" weapons.  One correction, however, is that the fragmentation lower limit on the 75gr hornady bullet is 2200fps, not 2300fps.  That's good for another 40-50yards.
Link Posted: 5/29/2006 5:33:52 PM EDT
[#7]

Originally Posted By SOSNBA:
All good information that correlates fairly well with my testing in 20" and 16" weapons.  One correction, however, is that the fragmentation lower limit on the 75gr hornady bullet is 2200fps, not 2300fps.  That's good for another 40-50yards.



Thanks for your reply.  What is your source for the 2,200 fps fragmentation threshold?

Molon
Link Posted: 5/29/2006 5:43:47 PM EDT
[#8]
Thanks for the great post!
Link Posted: 5/29/2006 5:44:21 PM EDT
[Last Edit: SOSNBA] [#9]
When Hornady sent me their brochure it showed effective ranges for their various loads.  The effective range for the 75gr looked like it corresponded to around 2200fps.  

I also found this while searching the web.

http://www.tacticalforums.com/cgi-bin/tacticalubb/ultimatebb.cgi?ubb=get_topic;f=78;t=001101#000001
Link Posted: 5/29/2006 7:15:12 PM EDT
[#10]
EXCELLENT work Molon and thank you for taking the time to share it with us.  First class write up all the way.  And yes that is my post on tacticalforums and yes it is accurate.
Link Posted: 5/29/2006 7:16:32 PM EDT
[#11]
Superb analysis!  Well done!!!

AC
Link Posted: 5/29/2006 7:31:20 PM EDT
[#12]

Originally Posted By wyv3rn:
EXCELLENT work Molon and thank you for taking the time to share it with us.  First class write up all the way.  And yes that is my post on tacticalforums and yes it is accurate.



According to your post on tacticalforums the fragmentation threshold is "2200fps +/- 50fps for manufacturing variances."  Being the conservative individual that I am, I am going to go with the "+50 fps" and post a table using 2,250 fps as the fragmentation threshold.  Thank-you greatly for the information.

Molon
Link Posted: 5/29/2006 7:56:21 PM EDT
[Last Edit: wyv3rn] [#13]
Actually, I should be clear.  At the time I responded to the OP, I was unaware their 5.56mm ammunition used a different bullet (the T2).  I thought it was the same projectile I had always shot loaded to higher pressures.  The 2200fps +/- 50fps figure I got from talking to Hornady reps was regarding their Hornady TAP Red Box 75gr .223 pressure (same projectile as used in TAP FPD).  However, I reviewed the test data I have on Hornady TAP 75gr 5.56mm T2 and their claims for maximum performance range and it is the same for a given velocity.

For instance:

Hornady TAP 75gr Red Box .223 pressure from a 20" barrel:
Hornady's data: 2663fps, claimed max performance range 225 yards

Hornady TAP 75gr 5.56mm T2 from a 14.5" barrel:
Hornady's data: 2667fps, claimed max performance range 225 yards

It is possible that the BC for the T2 projectile is slightly lower (it appears less aerodynamic to me anyway but this is only an eyeballed guess and you know what those are worth) but also has a slightly lower fragmentation floor to compensate.  Although, I kind of doubt it.  I'm pretty sure DocGKR would've spanked me if the data was wrong.

Also, as for the BC of the "non-T2" (does it even have a name?  T1?) 75gr projectile, you may want to consider my comments in this thread:

www.ar15.com/forums/topic.html?b=3&f=16&t=282084

I personally don't believe their claim of .390 BC for the current 75gr projectile used in their .223 pressure load.  More like ~.340.

ETA:  When I use your numbers (environmental, BC of .389/.350, velocity) in my ballistic calculator I'm consistently reaching 2300fps 8-14 yards further than where you are hitting 2300fps.  Not saying my ballistic calculator is more right than yours, just wanted to add that bit of info.
Link Posted: 5/29/2006 8:25:56 PM EDT
[#14]
In another one of Rick Jamison's excellent articles in Shooting Times, he posted the results of his testing of the Black Hills 75 grain OTM load.  He chronographed SIX 10-shot groups at 200 yards and determined the ballistic coefficient for each group.  The overall average BC for all six groups was .352.  This is incredibly close to the BC of .350 that I used for the T2 bullet.  

The BC of .389 for the TAP FPD bullet does seem a little generous.  Until I can do some long range chronographing of the TAP rounds (or someone else does and posts their results) I think I'll stick with these ballistic coefficients and use the more conservative fragmentation threshold of 2,250 fps.  (Table to follow)
Link Posted: 5/29/2006 8:30:20 PM EDT
[Last Edit: wyv3rn] [#15]

I think this shows quite nicely the validity of using 10-shot strings for chronographing.


It also shows how consistent Hornady's TAP ammo is.  As of late, even their lot-to-lot variation is damn near, if not, nil.  IMO, Hornady TAP ammunition is hands down the best factory loaded ammunition .223/5.56mm I have ever used.  I don't use the FPD hardly at all though so I can't comment on it as far as consistency.  I don't like the black nickel coating.  I know it is probably a harmless non-issue but it appears to chip off during the firing cycle and I just don't like that when I can get the red box.  Other than that what experience I did have with it was good, very accurate and shot to the same POI as the Hornady TAP 75gr Red Box .223 pressure.

I also wanted to add to my comments that this write up is missing NOTHING that I can see or think of at this time.  Everything is foot noted where it should, detailed environmental conditions are given, etc.  I'm a real stickler for that kind of thing.  You are certainly to be commended for the quality of your work.  My own notes are often messy because I have so much crammed in to one day of testing, but they are detailed and atleast I can read them just fine.
Link Posted: 5/29/2006 8:48:35 PM EDT
[#16]
Nicley done.  Thanks for putting all of that together.
Link Posted: 5/29/2006 9:37:52 PM EDT
[#17]

Originally Posted By Troy:
That's a first-class comparison.  smiley.onegreatguy.net/thumbup.gif

-Troy



My first +1. Fantastic post, nice job on the layout, very easy to read and follow.
Link Posted: 5/30/2006 3:31:23 AM EDT
[Last Edit: wyv3rn] [#18]
I believe I found that article by Rick Jamison you referenced.  It is indeed a good article, thank you for the lead.

www.shootingtimes.com/ammunition/bh_080305/index.html

Notice the 80gr projectile is the only one that even comes close to a BC of .390.  Personally I'd use the average BC of .353 for the Hornady 75gr "T1" for both projectiles for now.  I know the barrel the projectile is fired from and the velocity at which it travels effects the BC of the projectile (all barrels mark and launch the bullet differently) but it shouldn't be too much difference and .353 is a hell of a lot closer to the real mark than .390 IMO.

ETA:  He used a Krieger 1:8 match barrel for his tests of the BH 75gr load which had a muzzle velocity of 2744-2834fps.  On average, a standard grade 4140, 4150, CMV, etc. chrome-lined barrel will mark and deform the bullet to a greater extent and lower the BC even more.  In other words, his BC measurements are likely to even be a best-case-scenerio BC measurement.
Link Posted: 5/30/2006 4:21:43 AM EDT
[Last Edit: DevL] [#19]
It is my understanding that much like M193 traveling through the 2700 to 2500 fps range that the Hornady 75 grain OTM bullet fragment violently at 2300 and above and fragment less (can still break at cannelure) and with less reliability down to 2100 fps.  This would be an average of 2200 fps for a performance envelope. Right?

What range was the chrono measurement taken at?  Did you add that range back to the fragmentation range when you gave it or jaust base it off the chrono speed minus velocity lost at range?

Where did you get the BC for the T2 bullet? EDIT: I SEE NOW ITS JUST A GUESS... does Hornady not have the BC info for the projectile?  Are you brave enough to put your chrono out at 100 yards and take some measurements?
Link Posted: 5/30/2006 4:38:11 AM EDT
[#20]

Originally Posted By wyv3rn:

On average, a standard grade 4140, 4150, CMV, etc. chrome-lined barrel will mark and deform the bullet to a greater extent and lower the BC even more.  In other words, his BC measurements are likely to even be a best-case-scenerio BC measurement.



Where did you get this data?  I know in other calibers with high velocities and thin jackets people will NOT use cut rifled barrels because they will cause enough jacket damage to casue the projectile to break up.  So your claim is just the opposite of what I have heard from some other long distance shooters. I am just repeating what I heard so I wondered whre the data comes from/what the real truth is.
Link Posted: 5/30/2006 4:39:51 AM EDT
[Last Edit: wyv3rn] [#21]

Originally Posted By DevL:
It is my understanding that much like M193 traveling through the 2700 to 2500 fps range that the Hornady 75 grain OTM bullet fragment violently at 2300 and above and fragment less (can still break at cannelure) and with less reliability down to 2100 fps.



My understanding is this.. The reliable fragmentation floor is 2200fps +/- 50fps for manufacturing variances.  This means all will _reliably_ fragment at 2250fps, but some lots may fragment reliably down to 2150fps.  When the velocity is lower than, but relatively close to the reliable fragmentation floor, whatever it may be for that lot, fragmentation is possible, but a crap shoot (unpredictable).  I suspect by manufacturing variations they mean the exact composition of the copper jacket, the lead core, jacket thickness, cannelure depth, exact gel calibration, what the individual barrel does to the bullet, etc.  All of these things have tolerance ranges and vary atleast a little.  If you had one lot with all the tolerances stacked in one direction and another lot with all the tolerances stacked in the other direction I could see how there could be a 100fps range of variation in reliable fragmentation floor.  Match projectiles even vary in weight by a tiny fraction of a grain here and there.  I am aware of some testing on the Nosler 77gr in which it fragmented as low as ~2050fps but it was not considered a reliable fragmentation floor because it was not tested across multiple lots and not more than a few times at velocity.

ETA:  We must also remember that the whole 2200fps +/- 50fps figure almost definitely follows a Gaussian distribution where, for example, 80% of the lots are actually something like 2200fps +/- 25fps, but the remaining 20% stretch the figure to 2200fps +/- 50fps.  In construction/manufacturing actual far-end to far-end variances are relatively (<-key word) uncommon and variable items (such as jacket thickness or the thickness something must be machined to, etc.) are somewhere in the middle 25%-75% of their tolerance range a majority of the time.


What range was the chrono measurement taken at?  Did you add that range back to the fragmentation range? Where did you get the BC for the T2 bullet? EDIT: I SEE NOW ITS JUST A GUESS... does Hornady not have the BC info for the projectile?  Are you brave enough to put your chrono out at 100 yards and take some measurements?


He said he did add the velocity difference back to his muzzle velocity.  I don't know about the fragmentation range.  Maybe that's why I am getting 8-14 yards further on the fragmentation range on my ballistic calculator using his numbers (me starting with his muzzle velocity, him starting with his chrono'd velocity)?  It could just be differences in the calculators' algorithms though.  Hornady does have their claimed BC info for the Hornady T2 bullet, it is listed in their LE catalogue.
Link Posted: 5/30/2006 4:58:56 AM EDT
[Last Edit: wyv3rn] [#22]

Originally Posted By DevL:

Originally Posted By wyv3rn:

On average, a standard grade 4140, 4150, CMV, etc. chrome-lined barrel will mark and deform the bullet to a greater extent and lower the BC even more.  In other words, his BC measurements are likely to even be a best-case-scenerio BC measurement.



Where did you get this data?  I know in other calibers with high velocities and thin jackets people will NOT use cut rifled barrels because they will cause enough jacket damage to casue the projectile to break up.  So your claim is just the opposite of what I have heard from some other long distance shooters. I am just repeating what I heard so I wondered whre the data comes from/what the real truth is.



Also just repeating what I've heard quite awhile ago, but FWIW I did hear this from a knowledgable match grade barrel maker.  I've talked to a handful over the years and I don't recall who it was that said that.  I know there is a conflict of interest here but none that I've talked to are known to be liars.  After seeing some bore scopes of true match grade barrels vs. standard grade for myself, I can definitely believe it.  Up close one's interior is smooth as glass the other looks like the Colorado rockies by comparison.
Link Posted: 5/30/2006 7:11:37 AM EDT
[Last Edit: DevL] [#23]
Im not talking match vs milspec I am talking cut vs button rifled.  Example... Which deforms the bullet less, a single cut Krieger or a button rifled PacNor?
Link Posted: 5/30/2006 9:34:12 AM EDT
[#24]
Excellent post, thanks for sharing this info!
Link Posted: 5/30/2006 10:50:49 AM EDT
[Last Edit: Molon] [#25]
The ballistic coefficients that I used were not “guesses.”  As stated in my first post, they were estimations extrapolated from Hornady’s ballistics tables.  For example, Hornady gives the following information in their ballistic table for the 75 grain TAP FPD round.

Muzzle velocity: 2790 fps
Zero: 200 yards
Trajectory at muzzle:  -1.5” (height of sights above the bore line)
Trajectory at 300 yards: -8.30”

Since no atmospheric conditions are given I used the “Standard Atmospheric Conditions” for ballistics.*  Punching the first three data points into an exterior ballistics calculator program and adjusting the ballistic coefficient until the trajectory matches -8.30” at 300 yards yields a ballistic coefficient of .389.



*Stand Atmospheric Conditions for ballistics.

Altitude:    Sea level
Barometric pressure:   29.53 inches Hg
Temperature:    59 degrees F
Relative humidity:   78 percent
Link Posted: 5/30/2006 10:51:24 AM EDT
[Last Edit: Molon] [#26]
I debated with myself whether or not I should even include the fragmentation table in this thread.  There are so many variables involved with something like this (no doubt many that I am not even aware of) that it can never be exact.  Since I did not do actual gel testing myself I was reluctant to post on the topic of fragmentation, but, I wanted to know what a conservative estimate of the ranges that I might expect reliable fragmentation to occur with the rounds being tested and I thought other persons might be interested in such an estimate as well.

There are no guarantees in the world of terminal ballistics.  Those who have done extensive gel testing have found that the results can be highly variable.  Tiny and relatively unpredictable factors such as the angle of bullet yaw when striking the target can have a major effect on terminal performance.  Below are some of Dr. Martin Fackler’s wound profiles for M193.  In approximately 15% of occurrences, M193 does not reach maximum temporary cavitation until 25cm (9.8 inches) of penetration (the bottom wound profile).  The upper torso of the average adult male has an anterior-posterior diameter of 9.5 inches (see the picture below).  Thus, in 15% of straight-on shots with M193 the round won’t even reach its maximum cavitation point until it has sailed through the back of the target.  With so many variables involved, trying to narrow down the fragmentation range of TAP rounds to within a few yards would probably require more resources than most of us will ever have.





Link Posted: 5/30/2006 11:55:55 AM EDT
[#27]
Thanks for the great report, I didn't realize the two types were that different. I thought it was mostly a marketing thing.
Link Posted: 5/30/2006 1:57:17 PM EDT
[Last Edit: Molon] [#28]
I just got off the phone with Hornady and they said that according to an employee named "Dave," who they stated designed the new "T2" bullet, the ballistic coefficient for the T2 bullet is .361.
Link Posted: 5/30/2006 3:45:19 PM EDT
[Last Edit: Molon] [#29]
Here's a little tid-bit I noticed when inspecting the 5.56 TAP and TAP FPD rounds.  The meplats of the 5.56 TAP are incredibly uniform.  The overall length of the 5.56 rounds only varied by .005" for the 20 rounds that I measured (2.240" - 2.245").  The TAP FPD had a variation in overall length of 0.014" (2.240" - 2.254").

5.56 TAP



TAP FPD

Link Posted: 5/30/2006 3:49:47 PM EDT
[#30]
Just what I have been looking for, Thanks
Link Posted: 5/30/2006 4:29:01 PM EDT
[Last Edit: wyv3rn] [#31]
More good informatin Molon, thank you again.  If you want conservative estimates of fragmentation range, personally I'd use the .350-.353 BC for both loads and 2250fps as the fragmentation floor cut off.  My understanding is the Hornady 75gr and Nosler 77gr projectiles display much more consistent distance before initial yaw than either M193 or M855 which can indeed be quite variable within a given projectile, let alone the fact that I've seen multiple different incarnations of both (meaning heavy naked-eye-visible differences) depending on the manufacturer of the bullet.  Even the projectiles used in Winchester's Q3131 and Q3131A loads, which are supposed to be "identical" have glaring visible differences.

I understand your reservation about posting fragmentation range estimates.  On top of what you listed there are other variables.  Muzzle velocity is effected by the type of chamber, how used the barrel is, ambient temperature, suppressed or unsuppressed, lot-to-lot variation in ammunition, etc.  Environmental conditions such as low humidity, high barometric pressure, etc. destroy the projectiles ability to hold velocity and hurt fragmentation range .  IMO, the best you can do is use the conservative BC, fragmentation floor, your velocity numbers and standard conditions.  At that point it will be up to others to adjust for the velocity their particular barrel puts out and their environmental conditions.
Link Posted: 5/30/2006 4:43:41 PM EDT
[Last Edit: Molon] [#32]

IMO, the best you can do is use the conservative BC, fragmentation floor, your velocity numbers and standard conditions.


Stay tuned!
Link Posted: 5/30/2006 4:47:30 PM EDT
[Last Edit: wyv3rn] [#33]

Originally Posted By DevL:
Im not talking match vs milspec I am talking cut vs button rifled.  Example... Which deforms the bullet less, a single cut Krieger or a button rifled PacNor?



Oops, sorry DevL.  I should've read closer.  Well you have me there, I don't know.  This is the first time I've ever heard that Krieger (or other cut-rifled) barrels in certain calibers are unsuitable for use with thin jacketed match bullets.  I'm not even close that echelon of shooters, nor am I willing to dedicate the time or $ to get there, so I stay in the mil-std kiddie pool for the most part.  I don't know all the benefits and draw backs to cut-5R-polygonal-superfreak rifling.
Link Posted: 5/30/2006 5:02:55 PM EDT
[#34]
It just bothers me that ammo makers will sell a load called for personal defense, that is less than the military/police application ammo out there.

TXL
Link Posted: 5/30/2006 5:08:26 PM EDT
[Last Edit: wyv3rn] [#35]

Originally Posted By Molon:

IMO, the best you can do is use the conservative BC, fragmentation floor, your velocity numbers and standard conditions.


I think that's just what I'll do!



I just realized that even this is flawed as you are not going to get the same MV out of your barrel at 59*F that you do at 84*F.  But I can't think of a better way to do it and it should be close enough.  Both TAP versions are pretty temp stable and someone else's barrel might get a higher/lower MV at a given temp than your barrels so the data will never line up perfect for everyone anyway.
Link Posted: 5/30/2006 5:23:15 PM EDT
[#36]
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

Link Posted: 5/30/2006 5:43:06 PM EDT
[Last Edit: wyv3rn] [#37]
Right on!

My calculator gave the exact same results this time.
Link Posted: 5/30/2006 5:52:20 PM EDT
[Last Edit: DevL] [#38]
That was the frag chart I was expecting to see. I do find it odd the regular and T2 have identical BC...
Link Posted: 5/30/2006 6:12:43 PM EDT
[#39]
Well Hornady claims the T2's BC is .361, but they also claim the standard 75gr is .395 or there abouts which it is not.  Better to be a little conservative when estimating fragmentation range.
Link Posted: 5/30/2006 8:17:44 PM EDT
[#40]
Very nice Molon. Awesome information, presentation and pictures.

Can we get this thing tacked please?!?!?!

Scott
Link Posted: 5/30/2006 8:53:48 PM EDT
[Last Edit: SOSNBA] [#41]
Ok, here's Hornady's info/data for the 5.56mm 75gr T2 ammo:

======================================================================

+  Ammunition conforms to 5,56 M855 ammunition and propellant specifications for case mouth and port pressure in an M4A1 system.

+ Ammunition uses a crimped in Mil-spec No41 primer.  Primer push forces meet or exceed M855 specification

+  Ammunition is loaded with the proven Hornady 75gr BTHP bullet.  The bullet is cannelured and both bullet push and pull forces meet or exceed M855 specification.  Bullet has a unique ogive shape to facilitate reliable feeding.

+ Ammunition retains Hornady's proven match accuracy, with a factory specification in a 20" 1-7" twist 5.56 test barrel of less than 1 moa.

CAUTION:  THIS AMMUNITION IS MEANT ONLY FOR WEAPONS CHAMBERED IN 5.56 x 45mm NATO

14.5" Barrel

Muzzle = 2660
50yds  = 2535
100yds = 2413
200yds = 2180
300yds = 1960

16" Barrel

Muzzle = 2720
50yds  = 2593
100yds = 2470
200yds = 2234
300yds = 2011

======================================================================

Interestingly, no data was provided for a 20" barrel.

Have fun.....

Link Posted: 5/30/2006 9:07:02 PM EDT
[Last Edit: Molon] [#42]

Originally Posted By SOSNBA:
Ok, here's Hornady's info/data for the 5.56mm 75gr T2 ammo:

======================================================================

+  Ammunition conforms to 5,56 M855 ammunition and propellant specifications for case mouth and port pressure in an M4A1 system.

+ Ammunition uses a crimped in Mil-spec No41 primer.  Primer push forces meet or exceed M855 specification

+  Ammunition is loaded with the proven Hornady 75gr BTHP bullet.  The bullet is cannelured and both bullet push and pull forces meet or exceed M855 specification.  Bullet has a unique ogive shape to facilitate reliable feeding.

+ Ammunition retains Hornady's proven match accuracy, with a factory specification in a 20" 1-7" twist 5.56 test barrel of less than 1 moa.

CAUTION:  THIS AMMUNITION IS MEANT ONLY FOR WEAPONS CHAMBERED IN 5.56 x 45mm NATO

14.5" Barrel

Muzzle = 2660
50yds  = 2535
100yds = 2413
200yds = 2180
300yds = 1960

16" Barrel

Muzzle = 2720
50yds  = 2593
100yds = 2470
200yds = 2234
300yds = 2011

======================================================================

Interestingly, no data was provided for a 20" barrel.

Have fun.....




Excellent information!  Thank-you.  According to those numbers the bullet has
a ballistic coefficient of .355 throughout the 300 yard range.
Link Posted: 5/31/2006 11:22:48 AM EDT
[Last Edit: Molon] [#43]

Originally Posted By wyv3rn:
Well Hornady claims the T2's BC is .361, but they also claim the standard 75gr is .395 or there abouts which it is not.  Better to be a little conservative when estimating fragmentation range.



And again there's Rick Jamison's testing that shows the T1 has a BC of .352 and now the data supplied by SOSNBA shows that the T2 has a BC of .355.

Another interesting point from Rick Jamison's article is that his testing shows the 77 grain Sierra MatchKing has a BC of .340.
Link Posted: 5/31/2006 12:06:50 PM EDT
[Last Edit: wyv3rn] [#44]
Yep!

The 77gr SMK's BC was a suprise to me too, I thought it would be higher.
Link Posted: 5/31/2006 12:40:15 PM EDT
[#45]
Is there any info on the fragmentation of the 75gr OTM without a crimp grove?  I ask because I have been able to easily reach 2650fps from my 16" barrel with my own loads (I can reach 2680 but that starts showing bad signs).  I see no reason to adopt the TAP FPD round if it going to fall 120fps below what I can produce.  My only reservation is that I have not seen fragmentation data for the BTHP bullet they list at 75gr.

I wonder if the T2 profile will be availible to handloaders?
Link Posted: 5/31/2006 1:04:11 PM EDT
[#46]

Originally Posted By Grunteled:

I wonder if the T2 profile will be availible to handloaders?



I sent an e-mail to Hornady asking them that very same question.  They never replied.
Link Posted: 5/31/2006 2:08:39 PM EDT
[Last Edit: wyv3rn] [#47]

Originally Posted By Grunteled:
Is there any info on the fragmentation of the 75gr OTM without a crimp grove?



Yes, it fragments just as readily.  Sure the cannelure weakens the jacket more but it is a very thin jacket already so it is not necessary.  Infact a years ago the first Hornady TAP 75gr I shot did not use a cannelured bullet.  The cannelure was only added later.  The test data I have for both the cannelured and uncannelured Hornady 75gr are indistinguishable.


I ask because I have been able to easily reach 2650fps from my 16" barrel with my own loads (I can reach 2680 but that starts showing bad signs).  I see no reason to adopt the TAP FPD round if it going to fall 120fps below what I can produce.  My only reservation is that I have not seen fragmentation data for the BTHP bullet they list at 75gr.


Hornady TAP FPD uses a brand new case.  Even with a once fired case you are playing the odds that you get a case that might've been weak to start with, and then was fired in a rifle that stresses cases more than average.  Now, I know failures in once fired brass are one in a million, usually brass can take many loadings, but they do happen, I've seen it.

Second, the expense of adding a cannelure was done out of necessity, not luxury.  The same reason the military requires a cannelure.  Some say it is not necessary if you have enough tension on the bullet.  I've had some BH 75gr back before they put a cannelure on it that was extremely tight, it was incredibly difficult to pull the bullet.  Once I got it out, there were obvious signs the bullet had been really squeezed in there.  But I'd pick up another round out of the same box and could still push it into the case a lot easier than a cannelured round out of another.  It is true that you are unlikely to have a problem, but even great neck tension is not always enough especially when you have to load for a variety of guns which all vary in their function and the conditions they will be put under.  For reliability, the cannelure beats neck tension alone.

The third consideration is this.  Notice the TAP FPD does not use a crimped primer.. because it is only .223 pressure and is highly unlikely to pop a primer.  Once you start loading to 5.56 pressures though, a crimped primer becomes more important as the likelyness of popping a primer increases dramatically.  Hence the reason the 5.56mm TAP has gone through the extra step to have the primer crimped in place.

I am not knocking your hand loads.  There are advantages to hand loading, as you can tailor the load precisely to your gun.  I bet they are great and extremely accurate, but there are often other trade-offs/limitations as to what a civilian is able to produce on his/her own compared to the machines and materials the factories have at their disposal.


I wonder if the T2 profile will be availible to handloaders?


I wouldn't hold your breath.
Link Posted: 5/31/2006 3:59:58 PM EDT
[#48]

Originally Posted By wyv3rn:

Originally Posted By Grunteled:
Is there any info on the fragmentation of the 75gr OTM without a crimp grove?



Yes, it fragments just as readily.  Sure the cannelure weakens the jacket more but it is a very thin jacket already so it is not necessary.  Infact a years ago the first Hornady TAP 75gr I shot did not use a cannelured bullet.  The cannelure was only added later.  The test data I have for both the cannelured and uncannelured Hornady 75gr are indistinguishable.


I ask because I have been able to easily reach 2650fps from my 16" barrel with my own loads (I can reach 2680 but that starts showing bad signs).  I see no reason to adopt the TAP FPD round if it going to fall 120fps below what I can produce.  My only reservation is that I have not seen fragmentation data for the BTHP bullet they list at 75gr.


Hornady TAP FPD uses a brand new case.  Even with a once fired case you are playing the odds that you get a case that might've been weak to start with, and then was fired in a rifle that stresses cases more than average.  Now, I know failures in once fired brass are one in a million, usually brass can take many loadings, but they do happen, I've seen it.

Second, the expense of adding a cannelure was done out of necessity, not luxury.  The same reason the military requires a cannelure.  Some say it is not necessary if you have enough tension on the bullet.  I've had some BH 75gr back before they put a cannelure on it that was extremely tight, it was incredibly difficult to pull the bullet.  Once I got it out, there were obvious signs the bullet had been really squeezed in there.  But I'd pick up another round out of the same box and could still push it into the case a lot easier than a cannelured round out of another.  It is true that you are unlikely to have a problem, but even great neck tension is not always enough especially when you have to load for a variety of guns which all vary in their function and the conditions they will be put under.  For reliability, the cannelure beats neck tension alone.

The third consideration is this.  Notice the TAP FPD does not use a crimped primer.. because it is only .223 pressure and is highly unlikely to pop a primer.  Once you start loading to 5.56 pressures though, a crimped primer becomes more important as the likelyness of popping a primer increases dramatically.  Hence the reason the 5.56mm TAP has gone through the extra step to have the primer crimped in place.

I am not knocking your hand loads.  There are advantages to hand loading, as you can tailor the load precisely to your gun.  I bet they are great and extremely accurate, but there are often other trade-offs/limitations as to what a civilian is able to produce on his/her own compared to the machines and materials the factories have at their disposal.


I wonder if the T2 profile will be availible to handloaders?


I wouldn't hold your breath.



Thanks for the info on fragmentation.  I appreciate that.

Three points to address.  

1.) I never use once fired brass for these loads.  Only new or pulldown milsurp.  I do it for exactly the reason you stated.  Max loads in unknown brass is not something I do.

2.) The loads I'm shooting are within SAMMI spec.  Hornady may choose to load to a certain pressure and not above with what they use for powder, but I'm not exceeding SAMMI loads in those 2650fps rounds.  They are stiff but I don't think they quite hit 5.56mm land.  I have been able to get over 2700fps but not without pressure problems with any powder I have on hand.  Thus I backed down to 2650.  It takes a good bit more pwder to get to 2700 than people may think due to diminishing returns as pressure starts to increase.

3.) These are crimped using the Lee crimp die.  It crimps enough to create a very slight ring in the bullet and makes it VERY difficult to set the bullet back.  I developed this load with a crimp so I know that IS the velocity with the crimp mentioned.  Not ideal for accuracy but I wanted it to have the crimp.

The only feature I feel uncomfortable with is the primer crimp.  As a maximum load these do expand the pocket but I've never had one feel loose, back out or pop out completely.
Link Posted: 6/1/2006 1:39:53 AM EDT
[#49]
TAG
Link Posted: 6/1/2006 11:23:14 AM EDT
[#50]
More tid-bits.

The average case weight of the 5.56 brass is 97.2 grains.
The average case weight of the FPD brass is 97.1 grains.

The 5.56 TAP has a powder charge of 24.6 grains of ball powder.
The TAP FPD has a powder charge of 23.6 grains of extruded powder.
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