ASYM Precision Ammunition 75 grain Tactical OTM
[i]
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.[/i]
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 on-line.
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.
K&M 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.
continued . . .
