Range Report:  Black Hills MK262 Mod 1





The 77 grain MK262 ammunition produced by Black Hills Ammunition has been referred to as the most accurate mass-produced 5.56mm ammunition that has ever been type-classified and issued by the US Army.  Since its inception, genuine MK262 has been manufactured solely by Black Hills Ammunition.  For years, MK262 was only available to the civilian population as “seconds,” but more recently Black Hills has made first-run production lots available on the commercial market.  It is the first-run version of MK262 Mod 1 that I tested for this report.

MK262 Mod 1 is loaded in WCC 5.56mm brass and uses a cannelured version of the 77 grain Sierra MatchKing.  The round is charged with a proprietary ball powder.



The 77 grain MK262 Mod 1 projectile compared to the M193 projectile.






MK262 powder.  (The squares of the red grid measure 1/10 of an inch.)





The specification for accuracy testing of MK262 calls for multiple 10-shot groups to be fired; which is exactly what I like to do for a range report.  An accuracy (technically, precision) evaluation of the first-run MK262 Mod 1 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 the test-rifle 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 handguards of the rifle rested in a Sinclair Windage Benchrest, 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. The set-up was very similar to that pictured below.









The Wind Probe.





The test vehicle for this evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar Walther barrel.  The barrel has a 223 Wylde chamber with a 1:8” twist.

Prior to firing the MK262 ammunition, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 77 grain MatchKing.  That group had an extreme spread of 0.69”.







Next, three 10-shot groups of the MK262 Mod 1 were fired in a row with the resulting extreme spreads (from smallest to largest):

0.96”
1.12”
1.21”

for a 10-shot group average extreme spread of 1.10”.  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 for the 30-shot composite group was 0.33”.  For those of you who might not be familiar with the mean radius, I’ve posted some information about it here.



The smallest 10-shot group.






The 30-shot composite group.







I chronographed the Black Hills 5.56mm MK262 Mod 1 ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt M16A2 barrel.









Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot and then has its onboard computer analyze the data to determine if there is any statistically significant difference between the two readings.  If there is, the chronograph “flags” the shot to let you know that the data is invalid.  There was no invalid data flagged during this testing.

The velocity stated below is the muzzle velocity as calculated from the instrumental velocity using Oehler’s Ballistic Explorer software program. The string of fire consisted of 10 rounds over the chronograph.














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:  79 degrees F
Humidity:  37%
Barometric pressure:  30.12 inches of Hg
Elevation:  950 feet above sea level


The muzzle velocity for the 10-shot string of the Black Hills 5.56mm MK262 Mod 1  ammunition fired from the 20” Colt barrel was 2848 FPS with a standard deviation of 10 FPS and a coefficient of variation of 0.35%!

For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.  

For comparison (and to give you an idea of how good the CV is for this factory loaded MK262 Mod 1 ammunition) the mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.









….

i'm so glad to see you back in the game here!  thank you so much for all the effort



any plans on testing the new BH 77gr TMK?

I've read ALOT of your older posts and would like to thank you for all the info ( I won't call it "work" ), great stuff for a new guy like me , even though some of it gets so in depth it boggles my mind sometimes, but I am learning
BTW, what did you do to that Blain guy? LOL           link.

Thank you very much Molon, I really appreciate the time and effort you put in to deliver such useful information.

Thank you for this.

Excellent work. Is this the most accurate 5.56 load you've tested? I can only find results with 5.56 TAP T2 from your noveske barrel not this new rig which had a mean radius of 0.37".

Thank you for this thread. Will you be testing any other black hills loads? TSX?

Awesome.

Any plans to compare the MK262 Mod 1 to the new 5.56 pressured 77gr. TMK?

Thank you for the test. I recently picked up 200 rds of this but haven't had a chance to try it.

....

Three 10-shot groups of the 5.56mm TAP T2 fired at 100 yards from the same Lothar Walther barrel had a mean radius of 0.34".



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I tested the Black Hills 50 grain TSX load when it first became available.  When I get some spare time I'll see if I can dig up the data.  You can find some links to data on other Black Hills loads that I've tested here.



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As always, excellent work! Thanks for taking the time to post your results.

The forums need a subscribe feature that applies to individual user's posts.

I would subscribe to Molon's posts.

Any chance you'd run CBC or IMI 77gr 5.56 through a test like this (if you haven't already?)

Thank you for doing this.

thanks for doing this.

Personally I would like to see this as well. I'm willing to donate IMI to the test.

It's on The List.











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That or his own sub-forum. ''Molon's Findings''

Great write up. I tested this ammo in 10-shot groups and my accuracy was almost a mirror image of yours. I'll look for the sheet, but I had a 10 shot group of BH and a 10 shot group of IMI on the same paper. The IMI had a slightly smaller group size, but the BH had a notable smaller mean radius. I only fired 10 of each though. I'll post it if I can find the picture.

 
In for the results. I've been very pleased with the BH 5.56mm 77gr TMK's performance.













 

 
I just picked up some of that IMI Razor Core. I'm interested to see how well it performs during your tests, compared to the Black Hills loads you tested in this thread. If it does well, I'll likely order more (assuming Widener's still has it...)

I also would like to say Thank You for all your hard work.

It truly helps....  so much so that I consider your input to be more reliable than most anything else.

Again Thank you for using your time , money and effort and publicly posting your findings.

AR15 has a lot of other hard working members, sectioned bullets, ballistic tests.... remember to thank all of them.

Thanks for all the work,
cheers

Also interested in the Razor Core.  Just picked up 100rnds but haven't gotten around to shooting it yet.

I have some Corbon 55gr that is advertised at over 3000FPS. Have you shot the Corbon FMJ?

I have pored over your posts and read them many times going back and forth from topic to topic.  

I've learned a lot and very glad you returned.  


Thank you very much for the time and effort you put into this!

MOLON! Haven't seen you post in a while. Nice to see these post again and thanks for all the effort!

Great write-up, Molon.  It's always good to see your work.  You are a valuable resource, as some other guys that actually go out and test stuff.

I have about 300 rounds of CBC 77 gr ammo.  I'm hoping to shoot some 10 shot groups this Sat.  Do you have any of this ammo?

Thanks for posting these threads .

Looking forward to seeing your results.

Another great report! Thank you.

Molon,
I see you have the IMI MK262 ammo on your list to test.

I've informally shot some IMI at 100 yds. through a Wylde chambered Krieger Criterion chrome lined 16" mid-gas barrel and it shot 1.75" for (1) 10 shot group but so far only with a 2 moa Aimpoint. The Krieger 16" ss mid-gas barrel shot a 1.5" group with the same IMI load and my Sierra 77 grain handload with the  Aimpoint. No scope or chrono info yet. The IMI cases seem a bit soft and leaves a little brass on the bolt face and shows an occasional light ejector swipe but no other issues. It has sealed bullets and crimped and sealed primers and I suspect it is much faster than my handloads. I need to get out to the range.

Edited-I screwed up which rifle and what groups. Went back and looked again and now it's right.

Cool, thanks for the report.

Chronograph data added to the original post.

Thanks, Also Im curious as to which barrel you prefer after years of testing, Lothar-Walther or Noveske?

Molon, I have consulted your excellent posts for years.

you have brought an objective, scientific, and consistent format to consumer ammo testing.

Thank you for your careful work. You are a credit to the firearms community.

keep up the good work!-  TM

Count me as another member grateful for Molon's return. Sooo much data, it's great.
The objective and complete write ups do need their own sub-forum :D

Also count me as someone interested in the CBC 77 OTM; just ordered some from PSA. We'll see how long it takes to show up!

Krieger . . .






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The IMI clone had a muzzle velocity of 2866 FPS with a standard deviation of 21 FPS when chronographed from a 20" Colt barrel.

Molon:  I shot groups with my Colt LWT upper (6720) and it shot the CBC stuff like CRAP.  My particular upper shot XM193 and Fusion 62gr much better.  I have a Rock Creek (4150 CMV, 5R rifling, Wylde Tactical chamber (slightly larger than normal Wylde to ensure ejection of live rounds), CLE finished) barreled upper that I'm going to try out the CBC ammo in next.  I know that this ammo can shoot better than what I saw with the Colt upper.

 
My F-class and High power friends agree with you.


I picked up a LW 20" 1/8 twist Varmint Tactical barrel from Wally to use for my eval rig, and at some point I'll order a 20" Krieger as well.

Every barrel is a law unto itself.