16 or 20 inch barrel, i have both

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 military.  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 primer pockets are crimped and sealed.  Contrary to erroneous information that has been posted on the Internet, MK262 Mod 1 does not have case-mouth sealant.












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.)






Accuracy


The specification for the accuracy/precision portion of the lot-acceptance-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 used. 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”.








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” (1.05 MOA).  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”.  


The smallest 10-shot group.






The 30-shot composite group.






Velocity


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%.







….

Black Hills 5.56mm 77 Grain Tipped MatchKing Ammunition






The Black Hills 5.56mm 77 grain Tipped MatchKing ammunition is loaded with the same Sierra 77 grain Tipped MatchKing projectile that is available as a reloading component (#7177), with the addition of a cannelure.  The Black Hills ammunition was actually brought to market before the reloading component was.





The 77 grain Tipped MatchKing is the longest bullet (that I’m aware of) that is currently being loaded by a major manufacturer to magazine length for the 5.56mm cartridge.





With a nominal length of 1.070”, the 77 grain Tipped MatchKing is 0.335” longer than a 55 grain FMJ bullet and 0.085” longer than the standard Sierra 77 grain MatchKing.





Not only is the bullet itself long, but the ogive section of the 77 grain Tipped MatchKing is also extremely long for a bullet loaded to magazine length in the 5.56mm cartridge; so much so, that the grooves of the cannelure extend into the ogive of the bullet, as evidenced by the “arrow head” shaped cannelure grooves.  














The Black Hills 77 grain Tipped MatchKing ammunition is loaded in 5.56mm WCC brass that has the annealing iris still visible.  The primer pockets are crimped and sealed.  The case-mouth is crimped but has no sealant.  The load is charged with “ball powder.”








Velocity


I chronographed the Black Hills 77 grain Tipped MatchKing ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt M16A2 barrel with a 1:7” twist.





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 utilizes its onboard computer to analyze the data to determine if there is any statistically significant difference between the two readings. If there is a statistically significant difference in the readings, the chronograph “flags” the shot to let you know that the data is invalid. There was no invalid data flagged during this testing.

The velocities stated below are the muzzle velocities as calculated from the instrumental velocities using Oehler’s Ballistic Explorer software program. The strings 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: 72 degrees F
Humidity: 44%
Barometric pressure: 29.64 inches of Hg
Elevation: 950 feet above sea level

The muzzle velocity for the 10-shot string of the Black Hills 77 grain Tipped MatchKing ammunition fired from the 20” Colt barrel was 2808 FPS with a standard deviation of 14 FPS and a coefficient of variation of 0.50%.

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, 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%.





Accuracy


I conducted an accuracy (technically, precision) evaluation of the Black Hills 77 grain Tipped MatchKing 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 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 top of the free-float hand-guard. 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 accuracy 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  Black Hills 77 grain Tipped MatchKing, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 77 grain Tipped MatchKing (without a canelure). That group had an extreme spread of 0.68”.













the control group . . .





Three 10-shot groups of the Black Hills 77 grain Tipped MatchKings ammunition were fired in a row with the resulting extreme spreads:


1.26”
1.14”
1.37”


for a 10-shot group average extreme spread of 1.26”. 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 0.41”.



The smallest 10-shot group . . .





The 30-shot composite group . . .






MK262 Comparison

The table below compares the test results from this article to my previously obtained test data for Black Hills MK262 Mod 1 ammunition, which is loaded with the standard Sierra 77 grain MatchKing (with a cannelure.)







A.E.S = average extreme spread for three 10-shot groups at 100 yards

M.R. = mean radius for the 30-shot composite group

M.V. = muzzle velocity

S.D. = standard deviation of muzzle velocity

C.V. = coefficient of variation of muzzle velocity


…

The Guru has spoken.

TMK has a bigher BC and should travel more accurately further than SMK.

Is 77gr TMK still unobtainium?

I saw the MK262 Mod 1 next to the M193 and thought, "How do they get enough powder in the case to achieve significant velocity?

I was quite surprised to see 2800 fps.

I have not seen it anywhere in about a year.

I believe the third ( and by far most relevant ) type is the tan box military load.
Those are hard to find but pop up on GB on occasion.

The red box is the exact same thing, made on the exact same line as the rounds that go to the military.  The rounds in the red box go through all of Black Hills internal testing, they just don't go through the military's lot acceptance testing.

...

The issued tan box has higher velocity.
Can’t speak to all those other metrics though.

No , it doesn't.

Wish I would've bought some 77TMK back when it was available. Couldn't pull the trigger at $1+ per round

I had an order for BH 77gr TMK, placed on a site (can't even recall which site) since 2020. Sometime this Spring, they contacted me and said, "That order you placed? We're getting a small batch in. Are you still interested? Price has gone up ($75 or $77/box of 50 IIRC)."

They did ship it. It's the only time I've been able to get any since ~2019.

Yes. It’s not crazy different, but will save you several inches of wind drift at 600 yards with 10mph full value wind.

The bigger benefit, is it has a much lower velocity threshold for fragmentation than SMK. This effectively gives you 2-3x the range for reliable fragmentation. But it’s worse for barrier penetration. Though, if you think you may need to penetrate barriers, then a bonded bullet or a solid copper is a better option anyway.

The newer lots of the 5.56 TMK have been loaded progressively with a shorter and shorter OAL over the years and the accuracy has gone down along with the increased jump in my rifles with each newer, shorter lot. It is still the best stuff around and I have about ten boxes of it in the safe spread over 5 lots.

It only gets released once per year from what I have noticed. I buy 4 or 5 boxes when it comes out each year, regardless of price.

But for my precision needs, I load the 77 TMK to max length in Lapua brass, with CCI primers and 8208 XBR powder at about the same velocity. I reserve the Black Hills for duty/defensive use ammo.

Molon since Blackhills is not available how does IMI 77gr  compare ?     IMI 77gr is available at least.   Not cheep though.

IMI “Razor Core” 77 Grain OTM, LR, Mod 1







This load is topped with a 77 grain OTM bullet with a cannelure.  The case mouth is sealed and the primers are crimped and sealed.  When chronographed from the 20” Colt barrel, the load had a muzzle velocity of 2866 FPS with a standard deviation of 21 FPS.

A 10-shot group group fired off the bench from my Lothar-Walther barreled AR-15 at a distance of 100 yards had an extreme spread of 0.95”.








….

Note that the Tipped Matchking hollow point can underpenetrate at close range when fired from a 20” barrel. It’s excellent in a 16” barrel.

iirc, that's only the 69gr

The 77gr TMK underpenetrated from a 20” barrel in this video

https://youtu.be/cmciv3gtj8M

In my opinion, the TMK is the king of the hill for modern 5.56 ammunition and it isn't even close. Check out the ongoing thread on Rokslide if you require proof of results.

It's been posted numerous times on this site, but the recipe for 1:7" TMK accuracy is:
Good brass
Consistent primer
Book max or slightly over charge of 8208XBR
77gr TMK seated to 2.25-2.26"

If that load doesn't shoot very well in your rifle it's probably operator error.

TMK is about as obtainable as a Unicorn Fart.. Sierra told me that they are not making it because they are focused on making hunting ammo. And I was scratching my head like what did that have to do with anything as they where not available long before the start of hunting season..

That's odd... I wonder what might be the reason to focus on hunting ammo? Most of the hunters I know of only shoot 2 rounds a year (one to check zero and the other for their deer) out of a box of hunting ammo they bought 20 years ago.

Not that I'm any better lately... I have two 50 round boxes of the Black Hills 77gr. TMK and I'm holding on to it since it seems like it's discontinued at this point.

Is there a link to the rokslide thread, or a clue how to find it?  If that's kosher for the rules?

https://www.rokslide.com/forums/threads/223-for-bear-deer-elk-and-moose.130488/