View Full Version : Gas gun .308 powders
I'm looking to load some .308 for my 18" Stag 10.
Reading through my manuals, I was wondering since they all use bolt guns for their testing, is there anything I should consider before dropping powder?
I've been loading for lots of other cartridges, but this is the first time for .308 semi auto.
Brass is once fired Saltech. I'll be using CCI LR primers from several years ago. Bullet is Nosler CC 155.
Just looking for something accurate at the range, not competing and won't shoot past 400.
I've got 4 pound jugs of Varget and TAC and several 1 pounders of various Hodgden powders in my stash.
Varget or TAC will work fine. I'm fixin to whip up a IMR 4064 load with 155 TMKs for gas gun this week. This is to save the Varget on hand for the guns that really like it.
For Gas gun, I generally want a little less pressure for reliable cycling compared to hotter bolt gun ammo. And my sizing die is different. (more "bump" for gas gun shoulders to feed) I was using the same sizing die once, but got a lot of Lapua Case separations because I was sizing my bolt gun ammo down too much. Very tragic situation.
And 4064 was the most accurate we found for the gassers. Can use a lot of powders for 308 but we generally use 4064 for gas guns and Varget for Bolt guns. Obviously you can switch and swop but that is out experience.
PB
Thanks for the info.
I put a ladder together of TAC from 42.5-44.5. All my books show way different loads for a 155 BTHP.
I put my OAL at 2.78", leaves a bit of room in my Larue mags.
Is Saltech brass the same internal volume as USGI / LC brass ? ....I have never used it.
And I'd check the brass weight , compared to USGI / LC brass.
Just to be on the safe side.
BTW, How did the Saltech shoot for you and your rifle (s) ?... I still wish I had bought some.
Yeah. The brass variations can swing widely. Never tried Saltech though.
I don't have any USGI to compare it to, and don't really know how to measure case volume.
Saltech cases weigh between 175 and 176 grains.
I only bought 2 cans and regret not buying more. I'm not a great shooter, but out of my Stag 10 I get 2" 5-shot groups.
I don't have any USGI to compare it to, and don't really know how to measure case volume.
Saltech cases weigh between 175 and 176 grains.
Is that decapped weight? Or just fired? I can weigh some of my brass for a general idea. People put way too much worry in measuring case volume. I've NEVER done that nonsense.
(Weighed a decapped & cleaned Lapua, and it was 171.5 gr. So your brass is in the good range. I'm not a fan of the thin neck Win/Hornady 308 brass for my set up.
Sorry, that's the decapped weight, once fired, untrimmed (still in spec).
I’m real partial to 4064 in that cartridge for my gas guns.
H4895 is a great one if you have it. Also, very accurate for what they are the Hornady 150 fmjbt, that bullet will surprise you. If only out to 400, no issues. I have no problem hitting a 4" plate at 300 with the 716i
I’m real partial to 4064 in that cartridge for my gas guns.
Kinda mimics Fed GMM if you can stand to meter it. Never have tried H4895.
IMR 4064 is really where it is at for .308 gas guns. I shoot pretty much only 175gr bullets and use the MK318 Mod 0 (FGMM 175) recipe as a baseline.
Powder: IMR 4064 @ 41.7 grains
Bullet: 175gm Sierra Match King
Case: Federal
Primer: 210M
IMR 4064 is really where it is at for .308 gas guns.
It's been easier to come by in recent months too. It is a world class ass ache to meter, but it's good stuff. I did have a lot velocity swing of over 100 FPS between 8 lb jugs in the past few years, so I keep a close eye on lots.
Hit the range today. Brisk but beautiful morning in WY.
This is what I was able to do at 100 yards. I'm not a pro shooter, just going off what the Army tried to teach me.
Saltech brass, CCI LRP, Ramshot TAC.
18" Stag 10L with YHM ULT can and 3-10 scope.
ProChrono DLX at 10 feet.
Hopefully the pics are OK.
Brass pic is lowest charge on bottom, working up.
Thanks ahead of time for looking and offering any suggestions.
https://i.ibb.co/FxCZqxd/IMG-20230112-123619.jpg (https://ibb.co/X2M0k2G)
https://i.ibb.co/S7mVPHx/IMG-20230112-124114.jpg (https://ibb.co/7NprXBz)
Definitely have some swipes on the heads in the top row... and the one below it. That would say you're running warm on those loads.
Definitely have some swipes on the heads in the top row... and the one below it. That would say you're running warm on those loads.
Thanks. Yeah, I think I was a grain away from max. TAC may not be the powder for 155 grainers. I'll try to find some IMR 4064.
We've had the LMT gasser shoot very hot at below max. Depends on the barrel and the powder lot. Just takes a little experimenting to see what works best.
A little primer cratering as well on those max TAC loads.
And I mentioned volume because it can effect the max charge weights as well. .308 / 7.62x51 cases can have quite a swing in weight and internal volume.
FWIW, I don't measure case volume either, but to me, it is something to consider while getting high pressure signs early.
Older case volume data ( 1967 and current )... but
The chart used a typical lead core 165/168gr bullet.
69577
From this article.
https://www.shootingtimes.com/editorial/308-load-data-for-ars/368218
I walked into Shipton's Big R and they had a pound of IMR 4061. Looks like I'll be loading some of that.
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I walked into Shipton's Big R and they had a pound of IMR 4061. Looks like I'll be loading some of that.
A buddy and I were texting yesterday. His sweet spot is 44.0 gr with the 155 TMK. But with 4064, the lot swings are big. He had a 70+ fps swing. I'm going to test a load starting at 43.0 and maybe 43.5.
A buddy and I were texting yesterday. His sweet spot is 44.0 gr with the 155 TMK. But with 4064, the lot swings are big. He had a 70+ fps swing. I'm going to test a load starting at 43.0 and maybe 43.5.Interesting. I watched a video (Johnny's reloading bench), and he mentioned that FGMM changed from RL15 to IMR 4064 to get more temp stability. Is it more lot sensitive than most? Oh well, I'll burn through this pound and see what it does. Thanks for the constant helpful input.
ETA: He starts talking about it around 4:36 https://www.youtube.com/watch?v=GEOQATHtKS0
Interesting. I watched a video (Johnny's reloading bench), and he mentioned that FGMM changed from RL15 to IMR 4064 to get more temp stability. Is it more lot sensitive than most? Oh well, I'll burn through this pound and see what it does. Thanks for the constant helpful input.
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That is very interesting if it's true. We have a fair amount of 4064 and generally only use for gassers. But FGMM is legit and always shoots nicely. I'm excited to see what we get out of my Bolt gun with the 155's velocity wise because our buddy shoots them out off his 13.5 Scar. I hope they are smoking pretty good. Minus trashing brass and popping primers.
PB
he mentioned that FGMM changed from RL15 to IMR 4064 to get more temp stability. Is it more lot sensitive than most?
RL-15 was horribly temp sensitive than 4064 in the military tests for the 7.62 LR ammo. I have no idea why they still went with it. It wasn't even close.
4064 does have some lot to lot swings in velocity in my experience. Anymore these days, you can't buy just 1lb of powder and run it. If you can't get at least 5-8 lbs of a given rifle powder, forget it.
I have had decent results with TAC in my PA-10 using the Speer 125 gr TNT bullets (cheap and accurate). IMR-4064 is what I run with 168 gr Nosler BTHP’s in my bolt gun. I just scored some factory IMI 175 gr OTM ammo from Midway and plan to try some tomorrow in both to see if it might be worthwhile to try some heavier bullets. My attempts with TAC and heavier (150 - 168 gr) in the gas gun weren’t great, but I haven’t really tried IMR-4064 in it yet.
4064 should treat you just fine with heavier bullets. Better powder in general. Good luck.
PB
The only downside with 4064 is the kernels are long cut rice. I tried running it once in my Dillon 550b and it was a mess. Chargemaster only for me with 4064.
308TRUMPFTW
02-08-23, 08:53
I have had decent results with TAC in my PA-10 using the Speer 125 gr TNT bullets (cheap and accurate). IMR-4064 is what I run with 168 gr Nosler BTHP’s in my bolt gun. I just scored some factory IMI 175 gr OTM ammo from Midway and plan to try some tomorrow in both to see if it might be worthwhile to try some heavier bullets. My attempts with TAC and heavier (150 - 168 gr) in the gas gun weren’t great, but I haven’t really tried IMR-4064 in it yet.
TAC works fine in 308. I load 42 grains of it in military brass with 150 grain hornady bullets. Varget and 4064 are better though.
m1a_scoutguy
02-08-23, 18:41
Hard to find I would think but in my M1a I used and loved IMR 4895 ! 42 grns and a 168 Nosler or Sierra and it always shot sub-MOA in my Fulton NM. AR style could be different I'm sure.
Pretty sure the latest batches have been 4064, for some years now.
RL-15 was horribly temp sensitive than 4064 in the military tests for the 7.62 LR ammo. I have no idea why they still went with it. It wasn't even close.
4064 does have some lot to lot swings in velocity in my experience. Anymore these days, you can't buy just 1lb of powder and run it. If you can't get at least 5-8 lbs of a given rifle powder, forget it.
triggerjerk
02-11-23, 09:07
If you want same lot, better order a big jug. Last couple of orders of multiple pound bottles haven't been same lot. In fact, latest had a bottle with dicked up label. Can't say for sure whether the 4 pounds were 2 lot or 3 lot.....
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