MK262 mod 1 load data help

[colt191145lover]

Got some more data.
16 inch BCM ELW shooting IMI Razor core 77g over a magnetospeed.

4 shots
Avarage 2675 fps
High, 2695 fps
Low, 2649 fps
S.D. 21.2

[folk06]

Lots of good info in this thread! Currently waiting on a good day to get out and test some mk262 clones myself using xbr and tac. I have not shot any black hills mk262 but I have shot a ton of IMI Razor core 77 and have had really good results so that's what I will be comparing my hand loads to.

Some results I've seen from the IMI 77:
10 shot velocity avg was 2828 with a SD of 13 (20" barrel, 65 degrees)
Shooting 10 shot groups I've had Mean Radius numbers from .37 to .50 with the average probably falling around .43
Screenshot_20170415-115121.jpg

The IMI 77 is pretty good stuff for the money 73 cents/round buying in bulk, but I'm hoping to get slightly better accuracy out of my hand loads for 30 or so cents less per round!

DD lower with SSA trigger
Aero precision upper with 20" Larue stealth barrel

[markm]

Currently waiting on a good day to get out and test some mk262 clones myself using xbr and tac.

Forget XBR if velocity match is what you're after. I use it and load it pretty hot, but can't match Black Hills performance without getting blown primers and stuff.

[LMT/556]

Series 5 Shots: 10 NV20 75°F
Min 2755 Max 2807 BH
Avg 2782 S-D 15.6 MK262
ES 52

Series Shot Speed
5 1 2784 ft/s
5 2 2776 ft/s
5 3 2807 ft/s
5 4 2792 ft/s
5 5 2786 ft/s
5 6 2798 ft/s
5 7 2761 ft/s
5 8 2780 ft/s
5 9 2783 ft/s
5 10 2755 ft/s

I've bumped mine to 24.4 TAC Nosler 77 gr OTM 2.245 LC 41

Series 2 Shots: 10 CC77OTM 75°F
Min 2751 Max 2806 24.4 TAC
Avg 2771 S-D 17.6
ES 55

Series Shot Speed
2 1 2753 ft/s
2 2 2769 ft/s
2 3 2760 ft/s
2 4 2769 ft/s
2 5 2806 ft/s
2 6 2767 ft/s
2 7 2768 ft/s
2 8 2751 ft/s
2 9 2797 ft/s
2 10 2777 ft/s

+00.0 95 24.40 2771 1313 59647 8765 97.1 0.987 ! Near Maximum !

[NotDylan]

What's the mk262 clone load that I believe Mark developed that is working well for everyone on here?

Assuming it's a .223 load of course.

[markm]

What's the mk262 clone load that I believe Mark developed that is working well for everyone on here?

Assuming it's a .223 load of course.

If you mean my load, it's 23.4 gr XBR. That's over max, and powder lot dependent. Work up to it. Again... TAC is likely the better choice if you're after velocity.

[mgrs]

Here are a couple that I use; I'm chasing velocity a little bit as I like to shoot steel with it at 600-800 yards:

All shot in an 18" suppressed Douglas Barrel

77gr Nosler CC @ 2.25 in WIN NT Brass
Tula KVB556M Primer
23.4gr IMR 8208XBR
2680 FPS AV
13 SD

77gr Nosler @ 2.25, WIN NT Brass
Tula KVB556M Primer
24.3gr TAC
2767 FPS AV
9 SD

Accuracy is about the same. Like the TAC load better for the speed and that it is forgiving pressure-wise. I've never done this with 8208, but that same TAC load with a hot chamber and ammunition that had been sitting in direct sun in a clear box for hours on a summer day, got 2790 AV. The rounds were hot to the touch even before going in the rifle. Ejector swipes but no flattened, pierced, or blown primers.

Also have some 2000mr load data but would have to dig it up. IIRC it took heavy, compressed charges but got some incredible velocities with no pressure signs.

If loading with TMKs, I back charges off .2gr.

[markm]

Here are a couple that I use; I'm chasing velocity a little bit as I like to shoot steel with it at 600-800 yards:

All shot in an 18" suppressed Douglas Barrel

We shoot a .223 pressure 77gr load out to 1000 all the time. Accuracy and low S.D. took priority for us. Now if you're in a really windy spot... every bit of speed is helpful. Our spot is usually mild winds.

[MisterHelix]

The load I use for 77 grain projectiles is listed in the Hodgdon reloading data as "MAX" for .223. With this powder/charge in a 5.56 chamber I see no significant pressure signs.

The velocities listed are from a 16" barrel. From a 12.5" barrel it goes about 2,400fps.

So, not a MK262 "clone", but decent velocities for a .223 pressure load, and pretty low SD.


Nosler 77 grain CC
Hodgdon Benchmark @ 22.8 grains
CCI 450 (small rifle magnum)
LC brass

Ballistic Coefficient: 0.340
Bullet Weight(gr): 77.00

# FPS
4 2549
3 2559
2 2563
1 2557
Average: 2557.0 FPS
SD: 5.9 FPS
Min: 2549 FPS
Max: 2563 FPS
Spread: 14 FPS

True MV: 2566 FPS

[gunnerblue]

I shot this 10-round group yesterday out of my precision build with a 16” BCM 410SS barrel:

77 gr SMK
23.5 gr IMR 8208 XBR
LC once-fired brass (no prep)
Federal 205M
Redding Type-S FL die with 0.245 bushing
Forster Benchrest seater

Velocity ~2675
ES 30
SD 11

I’m not really concerned with ES anymore, but would love to find some Russian primers and see if I can tighten up the SD and group size.