AR10 175 SMK NOT varget load?

[Park ranger]

I tried to make 43.0 of varget Lapua brass and a BR2 shoot well in my Armalite NM AR10. It will shoot juggernaut great but not 175’s. 42.5 seems ok, just it’s slow at 2470 fps.

What say you about N140 or H4895? Can I break 2500 in a 20” barrel? Any suggestions? This will be a load for local 600 yard mid range sling matches. Thanks

 

[Zero333]

This load is for my M1A with 18.5" bbl. (308win chamber)
175 gr bullets I use 42.5 gr of W-748, 2.800"coal, and should be right around 2,500 fps in a 20" bbl in T-shirt weather. It really drops in velocity when it's below freezing temp, but the accuracy is still just as good no matter the outside temp.
I chose W-748 because gas guns are high volume shooting and I use it on my Dillon 650 because it meters perfectly through it's powder dispenser.

H-4895 was just as good at the same 42.5 gr. Just not as consistent in the XL-650 powder dispenser. It also got a few extra fps over W-748.
41.5 H-4895 wasn't bad either and also and got me 2,466 fps in 70'ish Fahrenheit temp with the 18.5" bbl.

 

[rijndael]

H4895 w/ 175:

IME:
Low Node: 42.0
High Node: 43.2

 

[mac86951]

I tried to make 43.0 of varget Lapua brass and a BR2 shoot well in my Armalite NM AR10. It will shoot juggernaut great but not 175’s. 42.5 seems ok, just it’s slow at 2470 fps.

What say you about N140 or H4895? Can I break 2500 in a 20” barrel? Any suggestions? This will be a load for local 600 yard mid range sling matches. Thanks

So many questions, but as an AR guy; I'll start off. Please describe your load development, and what is your overall length with 175s? I assume you're using Varget, 175 Sierra Matchings, BR2s and Lapua 308 large rifle primer brass.

-Mac

 

[Park ranger]

So many questions, but as an AR guy; I'll start off. Please describe your load development, and what is your overall length with 175s? I assume you're using Varget, 175 Sierra Matchings, BR2s and Lapua 308 large rifle primer brass.

-Mac

Well, load development for the 175’s wasn’t as good as 185’s. I loading to mag length trying to replicate M118LR, so 2.800”. I tried 42.5 of Varget at 600 yards and shot a high master score (198 I think) but they are kinda slow. Added 1/2 grain more powder (now 43) and it won’t hold the 10 ring on a Service Rifle High Power target. 2+ Moa at 100 yards bench confirms my sling experience in the match. Guess I could go up, but doubt too much further.

So looking for a powder that will get 2550+ within AR10 pressures, not Palma loads.

edit: M118LR will shoot 197-199’s in this gun in my hands.

 

[Jeff Porter]

Since you are shooting midrange and are single loading anyway … look at seating them a bit longer and getting a bit more case volume and tweaking the accuracy. Run a jump test from 2.750” up to the OAL that only has .250” of shank in the neck. Berger as a good plan for this on their web page for both tangent and secant ogive bullets. The SMK design typically doesn’t care about jump but I have seen some loads that tighten up and get rounder by adjusting the seating depth. Some even shorter than mag length. ( I.e.- 223 loads with H75 and NCC77 both shot better at 2.235” than the 2.250” standard )

fwiw- lots of info in the web that M118 LR used Re-15 and IMR 4064 at various times. If you can find those powders they may work too.

 

[PRShooter]

I had mine out this weekend and shot a ladder
18” ba barrel
175 smk
LC LR brass
210 primer
Ramshot Tac

41.8 is where I stopped, primers started to get flat, not terrible but it was evident. Mind you this was in mid 30* weather.
41.4-2496
41.6-2497
41.8-2502

 

[lb-ft]

Echoing what others have mentioned above. A internet search "Federal Gold Medal Match 175 load" does indeed reveal two iterations, both IMR 4064 and more recently, RL15.

Both have shot very well for me, and the node I found was within .2 grains of "The Load".