ASYM Precision Ammunition 75 grain Tactical OTM




Full Disclosure – It is and has been my long standing policy not to accept free ammunition, firearms or related equipment from manufacturers, wholesalers or retailers.  I do this so that there can be absolutely no claims of bias in my test reports.

On September 16th, Stan Chen, the owner of ASYM Precision sent me a very professional and kindly worded IM introducing himself and asking if I would be interested in receiving some of his ammunition for testing.  He made it very clear in his IM that there would be “no strings attached” if I chose to accept his offer.   I informed Mr. Chen that due to my above policy I would have to decline his gracious offer.

After perusing the ASYM Precision website, my interest in the ASYM ammunition was genuinely piqued.  I placed an order for some of the 75 grain Tactical OTM ammunition through the ASYM website using the name that is printed on my birth certificate.  Since Mr. Chen and I have never met in person, I’m certain that he wouldn’t know that name from Adam.  I’m quite confident that the ammunition that I received and evaluated for this article is of the same caliber (no pun intended) that any other member of the general population would receive when ordering.


Consistency is the key to manufacturing quality ammunition.  This includes not only the consistency of the components used, but also the consistency in which those components are physically assembled into a loaded cartridge as well as the consistency produced from the “recipe” used to create a favorable interaction between all the components and the rifle firing the ammunition.

No manufacturer can produce ammunition that will be accurate in everyone’s rifle.  Every barrel is a “law unto itself” and there are simply too many variables involved for a given load to shoot accurately from every rifle.  What a manufacturer can do to create ammunition that shoots well from a broad spectrum of rifles, is to use quality components, find a “recipe” that works in test barrels and for  several sample rifles and then produce that ammunition with the highest level of consistency possible.

The ASYM Precision 75 grain Tactical OTM ammunition uses quality components.  The projectile used in this load is Hornady’s 75 grain BTHP bullet with a cannelure, or the “T1C” as it is commonly referred to here at AR15.com.





The Hornady 75 grain BTHP projectile produces some of the best unobstructed terminal ballistics currently available for a .223 Remington load.




Courtesy of Dr. G.K. Roberts








Courtesy of B&T Ammo Labs.



The Hornady 75 grain BTHP projectile is also capable of delivering excellent accuracy.  The 10-shot group pictured below was fired from my Krieger barreled semi-automatic AR-15 at a distance of 100 yards using hand-loads of the Hornady 75 grain BTHP without a cannelure, or the “T1”.





Now, we can’t expect factory-loaded ammunition to shoot nearly as accurately as a hand-load that was tuned to our own barrel.  Also, the addition of a cannelure and case-mouth crimp to a match-grade bullet will have a degrading effect on accuracy; but that’s the price we pay for implementing this “anti-Murphy” technique to help prevent bullet set-back that might occur in a semi-automatic firearm.  In one test that I conducted using the 77 grain Nosler Custom Competition BTHP bullet, the average extreme spread of 10-shot groups at 100 yards increased by 24% with the addition of a case-mouth crimp into the cannelure.





The ASYM 75 grain load has a firm crimp at the case mouth.  An average pressure of 112 PSI was required to effect bullet set-back using a K&M compression gauge.  There is no sealant at the casemouth.


Compression gauge.






Consistency in bullet seating depth is an important aspect of accurate ammunition.  You might think that you could simply measure the cartridge overall length to assess the consistency of bullet seating depth, but this would be incorrect.  Open tip match bullets are produced with the jackets drawn from the base to the meplat, (the reverse of full metal jacket bullets.)  This process results in bullets that can have large variations in their lengths, however the variation is overwhelmingly in the very tip of the bullet and this is not an issue of quality control; it’s simply an artifact of producing an open tip match bullet.  As an example, it’s not uncommon for Sierra 77 grain MatchKings to have variations in length of 0.010” - 0.015”, yet the MatchKings have an excellent reputation for accuracy.  

The pic below shows the steps involved in drawing the copper jacket “cup” into a finished 75 grain BTHP bullet.



Courtesy of apb2772



The beast that produces the Hornady 75 grain BTHP bullets.



Courtesy of apb2772




The distance from the base of the bullet to the ogive is the critical dimension related to bullet seating depth and accuracy.  With match-grade bullets such as the Sierra MatchKing and Hornady BTHP this dimension is extremely consistent.  As an example, I measured the length of ten randomly selected Hornady 75 grain BTHP bullets.  The variation from base to tip was 0.008”.  Next, I measured the base to ogive dimension of those same ten bullets using Sinclair’s digital bullet comparator system.  For eight of the ten bullets, the base to ogive dimension varied by only plus or minus 0.0005”, that’s five ten-thousandths of an inch.  One bullet varied by plus 0.001” and another by minus 0.001”.  This all shows that the proper method of determining the consistency of seated bullet depth is to measure the dimension form the base of the case to the ogive of the seated bullet.


Sinclair digital bullet comparator system.




There are a variety of instruments available for measuring the dimension from the base of the case to the ogive of the seated bullet.  One very simple, yet effective tool in this category is the RCBS Precision Mic.





I pulled ten random rounds of the ASYM 75 grain load from the box and measured the cartridge overall length.  The average OAL was 2.245” with a low value of 2.241” and a high value of 2.248” for a variation of 0.007”.  Next, I measured the base of the case to seated bullet ogive dimension of those same ten cartridges using the RCBS Precision Mic.  The variation was only plus or minus 0.001”.


Concentric: having a common center. Think of concentricity as a smaller circle centered within a larger circle. The amount that one circle is off-center with the other is referred to as “runout” and is usually measured in thousandths of an inch when pertaining to ammunition.

Why does all this matter? The more concentric, or the less run-out that a loaded round has, the more likely it is to shoot accurately. The bullet needs to be centered in the case neck and the case neck must be centered on the case body. This all helps the cartridge align itself in the chamber of the rifle so that the bullet has a straight shot to enter the rifling.

Seated bullet run-out of a loaded cartridge can easily be measured with a concentricity gauge.  Using a NECO concentricity gauge, I measured the seated bullet run-out of the ten sample rounds of ASYM ammunition.  The average seated bullet run-out was 0.004”.  The spiderweb graph shown below compares the seated bullet run-out (in thousandths of an inch) of the ASYM ammunition with two other factory loads and one of my match-grade handloads.








NECO concentricity gauge.




The 75 grain ASYM ammunition is loaded in virgin Lake City 09 brass.  The brass shows the annealing iris commonly found on military ammunition (which has no effect on performance.)  The primers are neither crimped nor sealed.  Mr. Chen had this to say about the brass:

“We uniform all the necks in a separate process before loading, to keep neck tension as consistent as possible with this brass.  We inspect every piece of brass for presence of flash hole and other irregularities before loading.”  







For those of you who might be wondering about the circular indentations found on the caseheads of Lake City brass, they’re for the octal numbering system used at Lake City as part of the Small Caliber Ammunition Modernization Program (SCAMP). A numerical number is given to different positions around the case headstamp and the values are added together to give a number that indicates the station on which that particular cartridge case was produced.








After breaking down the ten sample rounds of the ASYM 75 grain load, I weighed the deprimed and empty cases.  The weights of those ten cases are shown below  in grains.

92.74
92.66
92.88
92.22
92.08
93.48
92.52
93.26
92.28
93.12

The average weight is 92.72 grains with a variation of 1.4 grains and a standard deviation of 0.44 grains.  The variation and standard deviation of this small sample are in-line with much larger samples of  Lake City 5.56mm brass from previous years.







The 75 grain ASYM load is charged with a flattened “ball powder.”  The powder has a bulk density of approximately 0.989 grams per cubic centimeter, giving the cartridge a loading ratio of approximately 93%.  With regard to the powders used in his ammunition, Mr. Chen said, “I worked closely with my powder supplier to get optimal powders for specific loads.  I buy specific lots of the powders, in large quantity, that meet my specifications...they know what I'm looking for, and alert me to specific lots that meet the spec.” I weighed the powder charges from the ten sample cartridges with the following results in grains.

23.62
23.66
23.14
23.66
23.70
23.74
23.66
23.70
23.64
23.56

The average weight is 23.61 grains with a variation of 0.6 grains and a standard deviation of 0.16 grains.







The sides of the individual squares in the red grid below measure 0.10”.





The pulled bullets from the ten sample cartridges were weighed with the following results in grains.

75.12
74.80
74.90
75.20
74.90
75.14
74.84
74.92
74.90
74.88

These bullet weights show a variation of 0.40 grains with a standard deviation of 0.13 grains.  For comparison, I randomly selected 10 bullets from a box of Hornady 75 grain BTHP bullets sold as reloading components (#2279) and weighed them with the following results in grains.

75.04
75.10
75.04
74.98
75.04
75.06
75.02
75.08
75.08
75.10

This sample of the bullets sold as reloading components shows a variation in weight of 0.12 grains with a standard deviation of 0.04 grains.

The table below shows the affect that some of the variations involved in loading ammunition can have on muzzle velocity.  The data was generated using Quick-Load.




Here’s a few more tidbits before we get to the test results.  The SAAMI minimum chamber specification for the .223 Remington is 1.4636”.  The ten sample cartridges of ASYM ammunition had headspace dimensions that ranged from 1.4636” to a maximum variation of minus 0.002”.








The Speer Reloading Manual states that “CCI primers provide optimum sensitivity when seated 0.003” to 0.005” below flush . . .”  On eight of the ten ASYM sample cartridges, the primers were seated exactly 0.004” below flush.  One primer was seated at 0.0035” below flush and another at 0.006” below flush.  Mr. Chen stated that the specific primers used in his ammunition were selected because “They deliver the right brisance for reliable consistent ignition of the powder, and the correct cup thickness/hardness to stand up to higher pressures and floating firing pins. He also mentioned, "As a side note, we visually inspect every single primer for presence of priming compound, anvil, and irregularities.”


One of the things that really impressed me about the information given for this ammunition on the ASYM Precision website was the way in which the velocity data was presented.  Most ammunition manufacturers only give the velocity of their ammunition as obtained from a minimum spec, 24” test barrel.  While this SAAMI standard is certainly prudent, it is not very helpful for most AR-15 owners.  

In addition to the 24” test barrel velocity, the ASYM Precision website also lists what I refer to as “real world” velocities; that is, velocities obtained from AR-15s with barrel lengths and chambers in common usage.  The website lists velocities from well known brands of AR-15s with barrel lengths of 20”, 18”, 16”, 14.5” and 10.5”.  I chronographed the ASYM 75 grain OTM load from Colt AR-15s with 20”, 16” and 14.5” barrels.  The average velocity obtained from those three barrels only differed by 5 fps from the average velocity of the same barrel lengths given on the ASYM website.







Chronographing of the 75 grain Tactical OTM 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.  As mentioned above, data was obtained from a Colt 14.5” M4A1 barrel, a Colt 16” 6520 barrel and a Colt 20” M16A2 barrel.





M4A1 barrel





6520 barrel





M16A2 barrel















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: 50%.
Barometric pressure: 29.83 inches of Hg
Elevation: 950 feet above sea level



The chronograph data is shown in the table below.  The average standard deviation for the three 10-shot strings is 18 fps.  For comparison, the mil-spec for U.S. M193 and M855 allows for a standard deviation of 40 fps.






For comparison, the ASYM 75 grain OTM load was chronographed back to back from the 20” Colt M16A2 barrel with Hornady’s .223 75 grain TAP FPD load and Hornady’s 5.56mm 75 grain TAP T2 load.  The results are shown below.









Accuracy Evaluation
of the
ASYM Precision Ammunition 75 grain Tactical OTM








*****

From Rick Jamison:

“There are stories of a single bullet that for no explained reason flies out of what might have been a tight cluster. This often occurs with a three-shot string and many times with a five-shot string. If you're lucky enough to fire a group without a flier, you can end up with a very tight group. However, usually what happens if another five or seven shots are fired to complete a 10-shot string, other bullets fill in the space between the main group and the flier to make a reasonably rounded group. Ten shots are a more reliable indicator when it comes to predicting what a load is likely to do in the future.

The problem with 10-shot groups is that when you report them, everyone thinks you aren't shooting very well or that the ammunition is not good because the group sizes are so much larger than three- or five-shot groups. Also, when we're firing three- or five-shot groups with a flier, it is only natural to assume that it was caused by a flinch or "pulling" the shot. Therefore, since the flier was our own fault, the tendency is to eliminate it from any reporting of group size.

This is one of the advantages of using a machine rest... The machine rest reduces the human element. After using this machine rest for several years, I have determined that a 1.5-inch 10-shot group at 100 yards... is a good one.”

*****

I performed an accuracy (technically, precision) evaluation of the ASYM Precision 75 grain Tactical OTM ammunition 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 the 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 barrel used in the evaluation was free-floated. The free-float handguard of the rifle rested in a Sinclair Windage Benchrest with the aid of a Sinclair fore-arm adaptor, while the stock of the rifle 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.   All rounds were fired from the magazine.  The set-up was very similar to that pictured below.







The Wind Probe




The test vehicle for this evaluation was a semi-automatic AR-15 with a 24” stainless steel Krieger barrel.  The barrel has a 5.56 Match chamber and a 1:7.7” twist.  






Prior to firing the ASYM ammunition, I fired a 10-shot control group using match-grade hand-loads topped with Sierra 55 grain BlitzKings.  That group had an extreme spread of 0.464”.







From a distance of 100 yards, three 10-shot groups of the ASYM 75 grain ammunition were fired in a row with the resulting extreme spreads:

1.21”
1.11”
1.29”

for a 10-shot group average extreme spread of 1.20”.  The three 10-shot groups were over-layed on each other to form a 30-shot composite group.  The mean radius for the 30-shot composite group was 0.40”.  For those of you not familiar with the mean radius, I've posted some information about it here.


The smallest 10-shot group













The 30-shot composite group






The graph below shows the trajectories of the ASYM 75 grain load from various barrel lengths.






....

Great write up, thanks Molon.

As always I love reading your reviews.

Once again, Very impressive work Molon. Arfcom leg-humpers have chased off some of the best contributors we ever had. I thank you for staying around. I reference your posts often.

As a matter of comparison, I lifted the following quote from your thread about Hornady TAP vs TAP FPD:

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.


It is interesting to note that the ASYM ammo, with velocity intermediate between the two hornady loads, also has precision intermediate between them as well.  Granted, the sample size was small, but interesting non the less.

That has to be the absolute BEST ammunition write-up I have ever read.

Each time you do a review it keeps getting even better.

NICE WORK!!!

Thank you very much for such a professional presentation!

At least 75% of my ammo knowledge has been gleamed from you!

That is a very impressive load.  The added velocity over other .223 loads with the outstanding accuracy is very compelling...

may have to order some

How much does this ammo go for....I have never heard of it before????????

http://store.chencustom.com/223_ammunition_s/36.htm

That ammo looks to be rather well made, and it obviously shoots pretty well...

Off of their webiste



First time I saw a company lowball their velocity.

Molon - Many thanks for your fine work!

If sighted in at 50 yards from your M4 barrel, where does it recross the Line of Sight?

The graph is now in the first post.

It's Stan.  He's a stand up guy.  I met him and spent some time talking with him at a class this past year.  I honestly wouldn't expect anything less from him.  

Molon
 As usual, a great write up! I truly enjoy reading your tests!

+1  

Thanks,

FB

What would this place do without you?

Thanks yet again Molon.

As always you add a lot to the site.
Thanks for all of you time consuming work.





Bill

Excellent write up!  I will be ordering some of this for sure!

I have been running Stan's ammo for the last 6 months, and have a few thousand ronds downrange of 55gr, 75gr, 77 gr, .45 and .308.

It is excellent ammo and we (EAG) will be able to supply ASYM ammunition to our students, drop shipped to them at class.

This is great ammunition.

Superb post.

Unless I missed it in the OP, what is the status of neck and primer sealant in this ammo?  It sounds like this would be very good long-term storage, SHTF stash ammo if it is sealed


Dammit...just saw it in the OP that there is no sealant at either the neck or primer and the primers are not crimped.  Answered my own question

Another excellent write up. Thank you so much for your attention to detail!

Awesome write up Molon!  


ASYM website  http://store.chencustom.com/Default.asp

I think the following quote from Mr. Chen illustrates his philosophy pertaining to this ammunition.

"I designed this round with functional reliability in AR/M4's as a paramount requirement . . . So with reliability taken care of, then from there offer accuracy which is suitable for the round's intended mission, and practical from a manufacturing standpoint."

Molon you don't happen to have estimates on fragmentation for this particular load do you?

I wonder what effect  getting the max spread of powder weights down from .6grains to .2-.3grains would have.

Based on the muzzle velocity listed in the first post, a conservative, reliable fragmentation threshold for the 20" barrel will be approximately 205 yards.

Thanks Molon

And 16' and 14.5" barrels?  Please?

I got unstupid and ran Molon's numbers through my Smartphone ballistic computer. But i'm getting numbers slightly off then what Molon gave me for 20" barrels. I used the ballistic coefficiant for the T2 bullet and i'm not sure how close that is to the TC1. But i got about 150yds for my 16" barrel.

16" barrel:  150 yards.

14.5" barrel:  130 yards.

Thanks!

I appreciate both your efforts and your continued posting here.

Molon-

Any plans to test ASYMs other loads?  Like perhaps the 70gr TSX ?

The List is pretty long as it is, but we shall see.

Nice.

Wow, that is nice...  

Yup.  It solves the logistical problem for some people, while at the same time assuring them of quality ammunition for use in classes.

Da nada.

Have you anything new to report on this ammo? You're literally the only review I can find on it. I was just wondering how this stuff is doing long term. I just bought some but was thinking about buying a bunch more. Problem is I want to grab it soon but won't be able to hit the range before then.

Forgive me, I haven't found it, but does this site have a Molon sticky where all his ammo reviews are in one spot?  If not, why?...


Found it in the ammo FAQ


Should be front and center, IMHO.  No offense intended to mods.

What a great review, thank you.
 

Da nada.  



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