We’re snowed in so I have some time to commit to this project.  I have a box 500 77gr SMKs and another of 69gr SMKs plus 4 or 5 powders I could try.  My goal is to find a load that will shot a consistent 1 MOA or better.  I use both a 18” and 16” LaRue Stealth barrels.  So far I’m thinking these loads will be a good starting point.

69gr SMK, 25.2-25.5gr of CFE223
77gr SMK, 24.4gr CFE223

I have achieved 1 MOA before but is was never consistent enough for me.  Will the above be a good start?

Thank you and merry Christmas!

Here for information.

First off, what powders do you plan on using?
I've developed accurate loads for the 77gr SMK's with Accurate 2520 and 8208XBR powder.
The velocity on the A2520 left a lot to be desired but very accurate.

I'm a big fan of Varget wtih 69 SMKs.   From memory I think I'm at like 24.5gr or something, roughly in the middle of the book load.  That is where they seemed to settle in the best for me.   I also have some good loads with IMR4895 that I've been playing around with as I like that a lot for my M1 Garand loads.  I ended up using a pretty hot compressed load there so would suggest you work up to it on your rifles if going that way.

Powders on hand:

Attached File

Not sure if this helps at all or not but here is what I use:

69 gr SMK
24.5 gr Reloader 15
CCI 41 primers

White Oaks service rifle upper
Rock River NM lower

At 100 yds with iron sights off a bench, I shot a 10 shot group at 0.94".

A slightly higher powder amount also shot under 1".

77MK
IMR 8208 @ 23.4
CCI 41 primers
LC brass
Crimp with Lee factory crimp die

Thanks, I just loaded that this morning.  As soon as I can get out of my driveway (I was shoveling snow and ice all day) I’ll give it a try.  I’m not crimping mine.

Not a very "precision" load but ...

Mixed brass (mostly PMC, some Norma, Hornady Frontier, Wolf Gold) trimmed to 1.750
WSMRL primers
24.0gr BLC2
62gr Hornady FMJ seated to cannelure with no crimp (single shot bolt gun, why add a step on my single stage)

Gives right about MOA for me in my Savage bolt gun

Same brass, primer, powder and the 60gr Sierra TMK seated with the same seater setting as the above 62gr FMJ shaves off maybe 1/8 moa from that

Note that this is barely at the starting load for this powder, so velocities will be a tad lower than you may think (about 2750fps from my 26" barrel)

Midsouth sells the 62gr FMJ for 11c/ea ...

Edit - this site says for BLC-2 and the 69gr MK 24.5 start to 26.5 max 2.235" COAL - https://shootersreference.com/reloadingdata/223-remington/

Here’s 23.4 gr 8208 XBR from my 16” LaRue Stealth barrel.  I also got .67” on my ladder test with 24.2 of 8208.

Attached File

23.5gr H4895 is sparks of Mjolnir.

24.2 grains TAC with a 69

23.9 grains TAC with a 77

Almost exactly the same for my tac loads, except 24 gr for a 77. But my most consistent 77 gr load is 22 grains of Benchmark in a piece of Norma Brass with a 450 primer seated to a 2.25 COAL or 1.85 CBTO. Here's a recent confirmation of that load thru a hodge podge of parts but a 20" Super Sniper Wilson Combat barrel. Pulled the 5th shot....ouch.

Id have to double check my notes but im pretty sure is my load as well.  I love xbr and smk's.

That’s a solid load for sure.

Except I don’t crimp 5.56. At least not since 1988.

Try this:
Without a crimp, carry a round over to your gun safe. Then, with one hand, and moderate pressure, press the nose of the cartridge against the gun safe. If the bullet does not set-back in the neck, you don’t need to crimp. If the bullet DOES set-back, you need to reduce the diameter of the expander-plug on your sizing die. Crimping should not substitute for inadequate or inconsistent neck tension. The 5.56 - with adequate neck tension - does not generate enough recoil to cause bullet-shift in the ammo-stack during firing.

A heavy crimp risks deforming the case-shoulder. A very light crimp, it won’t be enough to secure the bullet if you mash a round during cycling.

I get it that some shooters report that a crimp provides better accuracy. In isolated instances I won’t argue against anecdotes. Find what works for you. But my belief is that squashing the case neck after seating the bullet should NOT be needed for top quality 5.56 ammo. And query: Do BENCHREST competitors usually crimp their ammo? I believe the answer is that the overwhelming majority do not. Yet they do go to great lengths (lathing case necks) to attain CONSISTENT NECK TENSION.

I’ll close this spiel with one exception for the crimp-avoidance:

FLAT-BASE BULLETS

You may have to FLARE the case mouth a bit to seat a 5.56 FLAT-BASE bullet. Otherwise, you won’t be able to seat the bullet without shaving copper. In that instance, of course you will have to smoosh the flare down (“crimp”) in order to finish construction of a round. I generally avoid flat-base 5.56 bullets for this reason.

Mine is 23.6.  23.8 was even better but was blowing out 25% of my primer pockets

My reference load to test AR-15 accuracy is 24.5 grains of Varget with 69 grain SMK's seated @ 2.250".

Very accurate from a large number of barrels.

100% reliable feeding and function.

Slightly below SAAMI maximum pressure resulting in long brass life.

77gr SMK's
25.2 grains of A2520
Loaded to magazine length, 2.250"
Lightly crimped with Lee Crimp Die

This is basically a clone of the Black Hills Mk262 round.  

Out of my Ruger American Ranch 5.56 16" bbl, it's pushing 2750fps.  10 shots @ 100 yards is 0.83".  The rifle shoots sub-moa out to 500 yards (furthest I've been able to test it).

77 grain SMK
2.26 oal
Lc brass
Rem 7 1/2
21.7 grains AR-Comp
2650 fps
5 shot groups
.622”   4/11/22
.685”   6/4/22

18” SPR barrel

I just shot 5 groups, 5 shots each.  .87”.
77gr SMK
24.2 gr 8208 XBR

One group that screwed me up was 1.38

.223 Wylde Chambers:

24.4 Grains TAC Under Nosler 77 grain CC CCI 450 primer 2.250" LC brass
25.0 Grains TAC Under Nosler 69 grain CC CCI 450 primer 2.245" LC brass

Damn man, that's a hot load!
I thought I was pushing it at 23.7gr of XBR...
Do you have popped primers at all in summertime?

No, brass looked good.  That was the last of my 8208 and I don’t see it available anywhere.

I squeezed this group out of my Mk12 WOA barrel with 25gr of Varget and 69gr SMKs.

Benchmark and H322 have always given me good accuracy but the velocity is not always there.

This.

With a premium barrel and 69 or 77gr SMK you have to actually try hard to exceed 1moa with the following powders:

R15
Varget
8208xbr

Those + smk = magic

Here’s an archived thread about 77 SMK that I thought was super helpful

https://www.ar15.com/forums/armory/Powders-for-77gr-SMK-/42-534580/

Never tried the 77gr SMK, but have excellent results with 69gr SMK with both H335 and 748.

69gr Sierra's
- Varget (25.3gn)
- IMR4064 (23.4gn)
- RE-15 (24.6gn)

77gr Sierra's
- Varget (23.6gn)
- RE-15 (23.6gn)
- 8208XBR (22.2gn)

Those group the best for me out of my 18" AR (1:7 twist) and the 69gr Sierra's with IMR4064 (23.4gn) are probably the best in general out of my 20" .223 Bolt Gun (1:9 twist)

I found I’m getting match accuracy with the 53gr Hornady V-MAX.  It’s right with the SMKs.  I shoot .70” with a 18” LaRue Stealth barrel.

New barrel does the same as the last with my gf shooting.
24.Xgrs Varget and 69 SMK’s

I will echo 69 grain SMK with WIN 748 IME.