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POF .308 & GAP10 accuracy results with < 175gr. loads

fast_hand84

I make good rifles shoot bad groups
Minuteman
Jul 10, 2020
44
28
Wild Blue Yonder, Montana
I’m hoping someone can help me wrap my head around something that is driving me crazy with my .308 gas gun setup.

For reference, guns are run-of-the-mill POF Revolution 308, 16.5” 1/10 (fairly new) and a Gen1 GAP10 which has a few thousand rounds through it). I shoot only factory loads out of both.

So, I have scoured *countless* threads (mostly here, along with a select few other resources) that have stated, in no uncertain terms, that bullet weight/type/brand/color/smell/taste absolutely does not matter, and makes zero difference at shorter (sub-300yd.) distances. Period. Some have even gone so far as to suggest that, at 100 yards, groups from a premiere load (something along the lines of Copper Creek’s 190 VLD’s in Lapua brass) would be indistinguishable from the likes of the dirtbag stuff...Wolf or TulAmmo 150 FMJ’s. My experience has been just the opposite.

Both my POF and GAP are incredibly accurate (3/4 MOA) with Hornady 178 ELD-X and FGMM 175 SMK. Even being run by a scrub like myself, these rifles are so squared away that the dreaded transition from a bolt gun to semi was almost effortless.

All that changes, however, with a lighter bullet. Switching from FGMM 175 to 168 opens the formerly sub-moa groups up to 2”+ at 100 yards, and the results were consistent across three different shooters. When running even lighter loads (150gr.) you might as well just shoot from the hip, Rambo-style. Are these results typical for anybody else that runs these guns? I know that a 1/10 twist (typically) likes heavier bullets, but should I be seeing such a significant difference in accuracy at 100 yards?

I realize that was probably long-winded, but for those who suffered through it, thanks in advance for your insight, and for your patience.
 
I’ve posted this here before, but when my LaRue tOBR was a still 308, i first bought 175 FGMM like a normal person and proceeded to shoot 2 plus inch groups. The test target was shot with 168 FGMM and was .44x. I then bought a case of the 168s and proceeded to shoot a best group of .45x. So while I never beat it, the barrel hammered with that ammo. I went back to shoot the 175s and the groups opened back up. moral of the story is the barrel was pretty picky, maybe yours is too..?
 
I’ve posted this here before, but when my LaRue tOBR was a still 308, i first bought 175 FGMM like a normal person and proceeded to shoot 2 plus inch groups. The test target was shot with 168 FGMM and was .44x. I then bought a case of the 168s and proceeded to shoot a best group of .45x. So while I never beat it, the barrel hammered with that ammo. I went back to shoot the 175s and the groups opened back up. moral of the story is the barrel was pretty picky, maybe yours is too..?

You’re probably right, but it is very reassuring to hear similar stories about other really well made gas guns that can be finicky about ammo.
 
155s are usually a little easier to shoot well but that was a gas gun optimized load.
175 SMK & 185 Juggernaut from my GAP-10 are great. Not so much in POFs I’ve been around.

Shorter barreled POFs do better than longer barreled POFS w/heavier bullets in my experience.
130 TSX / SOST were outstanding in 16.5” POF for accuracy but aren’t the greatest for LR use.

Ammo used (bullet weight, propellant type / burn rate) in a gas gun will absolutely have an influence on accuracy and overall performance, even at 1-300 yards.
Internet is a wonderful source of misinformation that gets repeated until it is well known “fact / common knowledge”.
 
155s are usually a little easier to shoot well but that was a gas gun optimized load.
175 SMK & 185 Juggernaut from my GAP-10 are great. Not so much in POFs I’ve been around.

Shorter barreled POFs do better than longer barreled POFS w/heavier bullets in my experience.
130 TSX / SOST were outstanding in 16.5” POF for accuracy but aren’t the greatest for LR use.

Ammo used (bullet weight, propellant type / burn rate) in a gas gun will absolutely have an influence on accuracy and overall performance, even at 1-300 yards.
Internet is a wonderful source of misinformation that gets repeated until it is well known “fact / common knowledge”.

Thanks for the reply, that was very informative. I have yet to run any TSX through either gun, but I will definitely pick up some to try out very soon. The 130’s excellent short/medium range performance could actually be perfect for me, as I have been considering swapping the POF’s current scope (Razor HD 5-20) out for a 1-6 LVPO. The Revolution’s fast-handling and light weight is so impressive, it is almost a shame to have such a super heavy optic on it currently (Vortex is 37 oz.)

And unfortunately, your last statement is all too accurate. I hate that rampant, regurgitated misinformation makes up such a massive portion of the internet these days.
 
All of the above ammo I mentioned was gas gun optimized.

"Factory" in that it was loaded by a licensed manufacturer but not by any of the "common", big / bigger name manufacturers.
 
All of the above ammo I mentioned was gas gun optimized.

"Factory" in that it was loaded by a licensed manufacturer but not by any of the "common", big / bigger name manufacturers.

I’m on the same page, for sure. While most of what I have run lately has been big manufacturer loads (have had particularly good results with Hornady’s “Precision Hunter” 178 ELD-X), my go-to has been Copper Creek’s gas gun optimized loads. I will most likely use them again to load the 130 TSX.
 
Do you allow the barrel to "season" in to the lighter weights ( for that matter any factory load ) prior to shooting for groups ?

I have no quantifiable proof... apart from seat of the pants observations , after many, many long, long days at the shooting bench.

And watching groups slowly shrink... after those seasoning rounds.

But I have noticed groups consistently ( enough ) shrink after allowing said seasoning.

Fire the first 5 shoots... as a throw away group.

Then fire 5 for grouping.

Just a suggestion.
 
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3-5 rounds when changing propellant is usually needed for barrel to settle back in. You'll see this with chrono data also.

I try not to mix different propellants or jacket materials when shooting groups unless I can clean barrel before starting with new propellant / jacket material. Makes it better between my ears.

YMMV

GAP-10s were specifically geared for 175 ammo.
I have not messed with the POF Revolution, not sure how those are set up.

I don't think the grouping issue is just a function of propellant and / or jacket material, more a function of how the gas system is set up on each rifle. When rifle isn't running smoothly, accuracy suffers.
 
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3-5 rounds when changing propellant is usually needed for barrel to settle back in. You'll see this with chrono data also.

I try not to mix different propellants or jacket materials when shooting groups unless I can clean barrel before starting with new propellant / jacket material. Makes it better between my ears.

YMMV

GAP-10s were specifically geared for 175 ammo.
I have not messed with the POF Revolution, not sure how those are set up.

I don't think the grouping issue is just a function of propellant and / or jacket material, more a function of how the gas system is set up on each rifle. When rifle isn't running smoothly, accuracy suffers.

That is something I definitely haven’t been doing, or even considered. I’ll add that to my routine.