308 Winchester AR Only

Using sierra 155s I have Ar Comp and Varget. GRT showing Varget would be a little less pressure and more velocity. Any idea where to start with a gas gun? Looking at 45ish gr of Varget and 43ish gr of AR COMP.

jLorenzo said:

Using sierra 155s I have Ar Comp and Varget. GRT showing Varget would be a little less pressure and more velocity. Any idea where to start with a gas gun? Looking at 45ish gr of Varget and 43ish gr of AR COMP.

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What brass? Because there's a world of difference between Lake City and Winchester brass.

For Varget, Hodgdon's .308 Service Rifle data shows a starting load of 43.0 and 44.0 max charge.

IME gas guns are just different and won't handle the same charges as your bolt guns. The service rifle data is geared more toward the M1 and M14 rifles... But probably a good place to start with an AR-10/.308

Can't help you with AR-Comp. But I bet someone else can chime in.

Mike

I think 45gr Varget is top end; wouldn't start there. Not sure if that's what you meant. I topped out at 43.5gr in LC brass as previously mentioned. Varget is kinda slow honestly. I tried StaBall Match yesterday. 47gr was the max I could fit in a case. Book max is 48.7(C)

OkieMike said:

What brass? Because there's a world of difference between Lake City and Winchester brass.

For Varget, Hodgdon's .308 Service Rifle data shows a starting load of 43.0 and 44.0 max charge.

IME gas guns are just different and won't handle the same charges as your bolt guns. The service rifle data is geared more toward the M1 and M14 rifles... But probably a good place to start with an AR-10/.308

Can't help you with AR-Comp. But I bet someone else can chime in.

Mike

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Federal brass

JR1200W3 said:

I think 45gr Varget is top end; wouldn't start there. Not sure if that's what you meant. I topped out at 43.5gr in LC brass as previously mentioned. Varget is kinda slow honestly. I tried StaBall Match yesterday. 47gr was the max I could fit in a case. Book max is 48.7(C)

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I have loaded 46-47 with 155s in a bolt gun figured 45 would be ok, maybe I'll start lower

I will have to check my loads in my book. Ar comp does much better with lighter bullets like the 155 than heavier bullets.

JR1200W3 said:

I think 45gr Varget is top end; wouldn't start there. Not sure if that's what you meant. I topped out at 43.5gr in LC brass as previously mentioned. Varget is kinda slow honestly. I tried StaBall Match yesterday. 47gr was the max I could fit in a case. Book max is 48.7(C)

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Are you shooting that staball match load in a gas gun? What bullet, and group size? I've got a few pounds of the staball match that I'd like to try under 175-178 gr a-max's or eldm's.

NCHillbilly said:

Are you shooting that staball match load in a gas gun? What bullet, and group size? I've got a few pounds of the staball match that I'd like to try under 175-178 gr a-max's or eldm's.

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Yes. 155gr SMKs. I should caveat that I'm using LC brass so I don't think I got full utility out of it. If you look at Hodgdon's load data StaBall Match provides some of the highest velocities but I wasn't able to fit the book max in the case. I loaded 46.5gr and 47gr. 46.5 shot about .7" and 26-something fps. About like Varget. 47 was definitely compressed and it showed. The group opened up and SDs where all over the place. It's kind of like StaBall 6.5. That powder needs to be close to 100% fill for accuracy and good SDs. But it gets wild when compressed.

I think StaBall Match could be a great 308 gas gun powder but you need the right brand of case to use it. As weird as it sounds I think Hornady and Winchester are probably the best options to get the max capacity to use this powder. I'm just not using the right brass for it.

jLorenzo said:

Using sierra 155s I have Ar Comp and Varget. GRT showing Varget would be a little less pressure and more velocity. Any idea where to start with a gas gun? Looking at 45ish gr of Varget and 43ish gr of AR COMP.

Click to expand...

...some pressure test results I obtained. Brass was assorted year LC. Environment is tropical island, avg year round temp ~85F, Relative humidity ranges from 65-80% during daylight hours to 85-100% at night. AR-10 build w/16" CLGS tube & SLR AGB, standard carbine buffer system. YMMV