shooting an AR vs a bolt gun

[a0cake]

Are you wrapping your thumb around the pistol grip or placing it vertically along the spine / letting it rest against the receiver wall on the strong hand side? This is not necessarily gas-gun specific, but if you're moving from a traditional stock to a vertical pistol grip it may be something to look at.

[TehLlama]

It seems you've eliminated a fair amount of the mechanical side of the question, but I'm curious at what range are you shooting at 1.5MOA, and then what weight bullets are you running. It's not unusual for 53-55gr projectiles to group better out to 200m even in very accurate guns, and also not strange that certain barrels will dislike a certain brand/weight/ogive/sectional density projectiles.
Are your handloads running the same bullet as the factory ones?

I'm worse behind my SSA-E equipped Mk12 clone that the rifle itself is, but when I get the things Strow mentions right, it's barely noticeable, if not indistinguishable when I'm running something other than match ammo through that upper. I've also learned that that barrel likes the Hornady 75gr projectiles more than the PPU 75gr, but outclasses me completely using 69gr SMK from BH or PPU stuff.

[prodgi]

The grouping has been at 100yds, the handloads have been 52grain SMK, 68&75grain Hornady and 77grain Nolser. All powder has been Varget, all brass has been LC and all primers have been CCI400.Factory ammo has only been some 55grain? Hornady and XM193. I know the XM193 is not tack driving ammo but the results were basically the same as the other stuff.
Oddly enough the best groups I've had has been with the GI trigger before I dropped in the SSA-E. I have been fighting this thing for a while and got some advice from other shooters to get a trigger better suited for this type of shooting. I basicly just wanted to find out just what the limits were truly going to be with a GI trigger and after several months I thought I had found my NPA and opted to for the SSA-E thinking that it would have some postive and immediate effects on my groups. Well I'm tired of throwing money and parts at the problem thinking that I just need this or that and bolt it on and fix the issue. I know that I'm not doing something right, and there has been some good advice given that I will work on.
Thanks guys.

[strow]

I just had Noveske replace a brand new SS upper that would not shoot. 4 bullets, 4 powders, 3 factory match loads. None would do better than 1.5moa.

The replacement barrel shoots 24.5gr Varget, Win brass, Wolf primers, and 75gr Hornady BTHP into sub MOA at 400yd.

Sometime you just get a bad barrel.

Try someones rig that will shoot sub moa for them. If there rig will go sub MOA for you then it's an equipment issue.

[SteveS]

Your ar may not be as accurate as a bolt gun.

[lunchbox]

Your ar may not be as accurate as a bolt gun.

I was always lead to belive AR platform will be less accurate vs bolt gun. AR with its multiple moving parts, violent extraction(esp in carbine gas length) before bullet has even left barrel. The bolt action locks up completly until shooter cycles action, the only movment is trigger. So in order to get AR shooting like bolt, Its has to be set up with precision in mind (trigger,barrel,etc) to match bolt acc.

[MegademiC]

Try someones rig that will shoot sub moa for them. If there rig will go sub MOA for you then it's an equipment issue.

This is great advice - and conversely... get someone who can shoot ars better than you (a known moa-sub moa shooter or such) shoot yours. If they also get 1.5" group or close - you'll know its the gun. Make sure its properly put together - tight scope rings/screws and tight barrel nut. Even if you "know" its right - double check everything before dropping $ on replacement parts.

[fr3db3ar]

What twist is your barrel? I'll assume its faster than 1 in 9.

Currently my R-15 is running Varget, CCI400, LC brass, 55 Vmax getting 3/4 to 1 MOA.

It really sounds like you could have a component/ammo issue.

[lunchbox]

I always liked the heavier bullets with Varget esp 69gr hpbt and 77gr

[Cameron]

a Fulton Armory (Criterion) barrel.

I think you may have reached the accuracy potential of the barrel at 1.5MOA. I have personal experience with 3 different Criterion barrels and all seemed very close to 1.5" at 100yds even with good shooters and match ammo. I have also heard similar accounts from 3 others that have has the same experience with the Criterion barrels. I have shot much better groups (sub MOA) with both Lothar Walther and Noveske match barrels than with the Criterion. I no longer own a Criterion SS barrel and I am thinking of picking up another Lothar Walther in the future.

Cameron