M855A1 Accuracy and Velocity

[jetfire]

Combat Sustainment Support Battalion aka fobbit support dweebs that typically have sock-puppet morons or tryhard mouthbreathers for command teams, and between the failings of bad commanders plus getting shit on by the rest of the Army all the time, they usually have little motivation or morale. Hence, CSSB's tend to be (aren't always, but tend to be) rife with systemic rot across all things including supply discipline.
Basically, if I had to bet on where any given 'lost' item or equipment came from, and I had to pick an Army element without any other clues or knowledge of local units or anything else, I'd bet on it being a CSSB.

Ah, so like our LRS units, but with their fingers in more pies, since LRS doesn't touch ammo.

[DocGKR]

"Sometimes it gets misshipped, too. I remember a bunch of people finding a few in their m855 bulk Bass Pro type purchases"

Yup, this has occurred many times; we actually got quite a lot of M855A1 this way prior to COVID.

[WDR]

It’s entirely possible the OP acquired his legitimately via industry contacts “for science.”

I'd hazard an entirely uneducated guess that is the case here.

This kind of ankle-biting what-about bullshit is exactly what drives bona-fide experts away from P-F. So simmer down. Jeez.

Agree 100%.

I really don't give a damn about M855A1 other than "for science"... it's not readily obtainable for me, and there are better options for my likely uses (namely, self defense) available on the commercial market. At the same time, I love to see reports like Molon's because they are interesting and often educational. I think it would be prudent to not drive Molon away from P-F.

If M855A1 was available commercially at a reasonable price close to other 5.56mm ball ammo prices, I could see buying a case or three to add to the ammo pile. But it really isn't anything especially game changing. It's better for most (military) applications than older ball ammo, but not revolutionary enough for me to fork out dollars per round for the stuff.

[TGS]

We can't ALL bootlick. Some of us want our money's worth!

There's a difference between bootlicking, and being the boot that gets licked.

Thanks for all the free ammo, btw.

[Unobtanium]

There's a difference between bootlicking, and being the boot that gets licked.

Thanks for all the free ammo, btw.

You did your 4 years of service and earned every round you fired. On that note, thanks for your service, being as today is the day for that. I don't have an issue with my tax dollars supporting the military, just with them having to pay out for civil suits due to what the military does. (Liberty debacle).

[echo5charlie]

@Molon - thank you for the write up. I look forward to part 2.

[Molon]

Hand-Loaded M855A1 Accuracy


When M855A1 was introduced, we were told by people with “inside information” that this new load produced “match-like” accuracy, yet none of these people where ever able to show statistically significant data to support this claim. The test results that I obtained with M855A1 certainly didn’t show “match-like” accuracy.

The Crane Naval Surface Warfare Center has done extensive testing with M855A1 fired from AR-15s mounted in a massive, sliding machine-rest test fixture. The Crane Naval Surface Warfare Center is involved in developing special munitions and weapons for our warfighters. They’re not interested in sales hype, politics and propaganda; they’re only interested in facts. They’re not driven by profit margins; their goal is providing our Special Operating Forces with the best tools for accomplishing their missions. When it comes to evaluating the accuracy of ammunition Crane uses 10-shot groups.



With newly barreled Mk18 upper receiver groups mounted in the heavy sliding machine-rest test fixture, M855A1 was only able to produce a 10-shot group average extreme spread of 2.74” at 100 yards with an average mean radius of 0.85”. With a round count of 3,600 rounds through the barrels, M855A1 was only able to produce 10-shot groups with an average extreme spread of 3.84” at 100 yards with an average mean radius of 1.10”.

The Lothar Walther barrel that I used to test the M855A1 for this evaluation had approximately 3,350 rounds through it at the beginning of my M855A1 testing and as we saw it produced an average 10-shot group extreme spread of 2.07” at 100 yards. A 30-shot composite group of the M855A1 from the Lothar Walther barreled AR-15 had a mean radius of 0.63”.

People are often quick to point out that the lack-luster accuracy of legacy M855 manufactured at Lake City is due among other things to the fact that M855 is composed of three different components; the lead core, the steel penetrator and the copper jacket, yet people seem to gloss over the fact that M855A1 is also composed of three different components; the copper core, the exposed steel penetrator and the copper jacket.



We know that the M855A1 that the US Army based their accuracy claims on was not manufactured on the SCAMP machinery at Lake City and was mostly likely manufactured on the slower BAM machinery. The speed of the SCAMP machinery is significantly faster than the older BAM machinery.
The M855A1 that I evaluated was produced on the SCAMP machinery. These M855A1projectiles themselves showed quite a bit of variation. As an example, the base to ogive measurements were all over the map.
The picture below shows two M855A1 bullets that I pulled from the lot of ammunition that I tested. The bullet on the left shows a properly shaped base. Notice the beveled heel and the flat base. The bullet on the right has a “ridge” running around the bottom of the bullet and the base is recessed. Apparently, the speed of the SCAMP machinery comes at a cost.






The US mil-spec for the accuracy/precision of the M4 carbine firing legacy M855 from a machine rest allows for an extreme spread of 5.0” for a 10-shot group at 100 yards.




The US mil-spec for the accuracy/precision of the M4 carbine firing M855A1 from a machine rest allows for an extreme spread of 5.6” for a 10-shot group at 100 yards.



It seems rather odd that the M4 carbine needs to have a larger extreme spread to meet the mil-spec when firing the load that supposedly has “match-like” accuracy. Most of my accuracy evaluation data for Colt M4 carbines was lost in a tragic boating accident, but I was able to obtain a 1.24 MOA 10-shot group from a Colt M4 barrel using true match-grade hand-loads (albeit, this group was only fired from 50 yards).



Unlike caliber .30 and caliber 7.62mm ammunition, there has never been a National Match accuracy standard for caliber 5.56mm/.223 Remington ammunition.
In 1965, the caliber 7.62mm Match ammunition was standardized as M118. The 1965 lot of 7.62mm M118 National Match ammunition had an acceptance testing mean radius of 1.9” for 10-shot groups fired at 600 yards. At that time, this was the smallest acceptance mean radius ever achieved for National Match ammunition since records were kept, starting in the year 1919. Naturally, the ammunition was tested from machine-rested, bolt-actioned, heavy test barrels.



The composite target pictured below shows the twenty-seven, 10-shot acceptance groups (that’s 270 rounds!) of the 1965, M118 National Match ammunition fired from the test barrels at 600 yards. The small circle has a diameter of 6” and the large circle has a diameter of 12”.

[img]https://www.ar15.com/media/mediaFiles/28568/national_match_ammmo_600_yard_composite-3172985.jpg
[/img]
From American Rifleman, September 1965

[img]https://www.ar15.com/media/mediaFiles/28568/mean_radii_history_of_national_match_amm-3172984.jpg
[/img]
From American Rifleman, August 1962.


Everything else being equal, a mean radius of 1.9” at 600 yards would have a mathematical equivalent of 0.32” at 100 yards. Now, 100 yards is not 600 yards, but then, a semi-automatic AR-15 is not a machine-rested, bolt-actioned, heavy test barrel either, so I like to use the mean radius of 0.32” for three 10-shot groups fired in a row (30-shot composite group) at 100 yards as the threshold for match-grade ammunition in 5.56mm/223 Remington when fired from a semi-automatic AR-15. A mean radius of 0.32” at 100 yards is equivalent to an average extreme spread of 1.025” for 10-shot groups.

The first step that I took in developing a hand-load using M855A1 bullets was to cull the projectiles with the “ridged” bases.


Next, the bullets were sorted by weight. A group of the bullets within the mean weight were further sorted by their base to ogive measurements and the bullets within this mean measurement were used for the hand-loads.

The cases used for these hand-loads were virgin Lake City cases that were weight sorted. The necks of these cases were then chamfered, deburred and neck sized using a bushing neck die. The primer pockets and flash holes were uniformed. Priming was conducted using a Sinclair hand priming tool.

The cases were charged with powder using an RCBS Match Master powder dispenser and the bullets were seated on a single stage Forster press. 10 rounds of each increment of powder charge weights were used to develop a load at 223 Remington velocities. Almost any 5.56 load can be hand-loaded to shoot more accurately/precisely when down-loaded to 223 Remington velocities.




The hand-loads were fired from my bench-rest set-up using the same Lothar Walther barreled precision AR-15 used to test the factory loaded M855A1 and all my usual procedures were followed. The smallest 10-shot group produced in this test had an extreme spread of 1.14” and a mean radius of 0.427” (and a score of 100-10X). Not quite match-grade, but close enough to call it “match-like” I guess.




…..

[TiroFijo]

Excellent!

Expecting "match accuracy" of a bullet with this design, and loaded on high velocity machinery is a bit too much...

On a side note, the old M118 ammo used the same 173gr FMJBT bullet that the .30-06 used in the .30 M1 ball , manufactured by Lake City. Do you know if the bullets used for the M118 were selected?

[Wake27]

Interesting, I'm actually surprised at the Crane results. I've seen significantly better groups over many ranges with 855A1 so anecdotally, I would've expected match-like to be far more supported.

[DocGKR]

Nope. M855A1 has not consistently demonstrated "match" accuracy in any valid multi-shot, multi-group testing I have seen to date.