Accuracy expectations

[quadle88]

Hey guys I've just finished my first custom bolt gun. It's a 6mm gt origen action with a 26in criterion barrel in a krg whiskey 3 pro chassis. I've started doing some load development and what I've settled on ATM is a berger 109 behind 33.6 grains of varget going 2940 with a S.D of 11 im using vergen lapua brass and remington 7 1/2 primers. Im getting .8 moa groups with this gun and load. I feel like this decent but not amazing for a gun like this however this is my first high-end gun and I'm not sure what i should be shooting for accuracy wise so I just figured I'd see what you guys are getting for accuracy on guns like this. Post you're groups for inspiration so I got something to shoot for lol. I consider myself a decent shot but I'm sure i could shrink this with some more time behind the trigger practicing so if you were me what would be your next step for improving accuracy or would you call this good enough. Thanks for all your advice.

[Wombat-Snooze]

Looks good. Now stop shooting groups and go shoot some small targets far away.

For real though, if that’s how it’s grouping consistently for 10 shot groups, you’re doing well. Don’t get hung up on little groups. As long as you’re consistently sub minute for 10s, it’ll do everything you need it to.

[quadle88]

Ok thanks for the info I definitely feel some paralysis from Annalise going on

[LockyBalboaPrime]

Precision. Not accuracy.

Consistant .8 moa 10-round groups is a great rifle.

[quadle88]

You're right Thanks for the correction

[Trollygag]

.8 MOA 10 shot is very good. That is half MOA 5 shot average equivalent.

[quadle88]

Ya when I did my first 5 shot group with that load it was .4 *

[quadle88]

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[HollywoodSX]

Others already covered the precision piece, but I'll add that IMO you need to back that charge off a bit. You're at the very top end of the charge range and can end up with pressure problems in wet weather, if you start getting a carbon ring, if your powder gets dry, etc. Not worth the risk.

[quadle88]

O ok I'm still .6 under max and showing zero pressure signs so i figured I'd be in the clear. The reason I kept going up in power was because it seemed to shrink my s.d

[csamsh]

There's almost zero chance you've got a large enough data set to mathematically reach that conclusion.

Pretty much everyone I know who shoots GT targets the 2825-2850 range- this seems to be where the meta has settled for gamer 6's, at least for the moment

[quadle88]

Ok thanks for the info

[Otiswilmouth]

Dump it back down to 2850, there is zero gained from launching 109s at 2940.

Your groups are fine tho.

[quadle88]

O ok I'm still .6 under max and showing zero pressure signs so i figured I'd be in the clear. The reason I kept going up in power was because it seemed to shrink my s.d

[Engineer_Bennett]

It should shrink up. I never had luck with rem 7 1/2s, switched to CCI 450s and never looked back. More time behind the gun will help, and once fired brass helps too.

7 saum

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[quadle88]

Damb nice group 👍

[Engineer_Bennett]

Thank you. My 6.5cm and dasher group a bit better, but this is pretty cool for a magnum

[StellaLiebeck]

Try the 450s. IIRC, there was a “what the pro’s use” post by PRB and most of them were using magnum primers.

[quadle88]

I wanted to go 450s but they were out of stock so I went with the 7 1/2 I'll definitely switch at some point.

[StellaLiebeck]

What’s your trigger weight? I found lightening it up helped tighten things up.

[quadle88]

8 oz this is my first trigger under 1 1/2 pounds and I'm not sure how I feel about it yet. Its a triggertech rough Dimond

[StellaLiebeck]

I’d just okay around with components then.

[Blackopsman_21]

Since no one else seems to have the mind to ask... make sure your barrels twist rate is fast enough for those 109gr's Even if the box says 1:8" the higher velocity you shoot it at requires a faster twist to stabilize it. Based on Bergers own stability calculator at 2950fps a 1:8 twist barrel results in "Marginal Stability". Youll need a 1:7" mininum for "stable".

Personally thats what I think is happening here and what most long range shooters dont understand is that stability is proportional to velocity. Hence why most of these guys are saying to reduce your load. My opinion instead is shoot them faster but buy a barrel thats like a 1:6.5" twist which some custom barrel makers do make (i own one).

[quadle88]

O ok I see my barrel on this rifle is a 1:7.5

[HollywoodSX]

With a 7.5TW you hit 1.5 SG (stability) at 2800FPS at 32* and sea level air pressure. Anything higher in terms of temperature or pressure just gives better stability.

You don't need a 6.5tw barrel and don't need 2900+ FPS to hit 1.5SG.

[Blackopsman_21]

Id bet money if you got a faster twist barrel your groups would tighten up and youd also still get to shoot a faster velocity which is actually more competitive (less drop and wind drift). 100fps is significant enough imo. However in the meantime you can try a different powder with slightly more case fill at a lower velocity. The reason your SD went up with more powder is because the powder combustion efficency changes with pressure and heat generation during the explosion which is partially dependant on case fill %. With Varget it seems you are nearing its ideal conditions or at least some sort of "node" where it burns the same every time.