Accuracy problem.

[netchemica]

http://i.imgur.com/8K3ss0c.jpg

This is the AR I built for long range. I'm anticipating building a 20" AR further down the road that will wear this Leupold scope, and this one will wear a lower magnification optic.

This is what it has on it (copy/paste):
Rainier Arms upper and lower
Rainier Arms Match 16" Mid-Length Barrel (.223 Wylde with 1in8 twist)
Vortex Flash Hider
Centurion Modular Rail
Leupold Mark IV 4.5-14x40 sitting in a Larue LT-104
Magpul UBR
BCM Charging handle Mod4 and pistol grip Mod1
Geissele Hi-Speed National Match trigger
Harris LM-S Bipod

Here is where the problem comes in. It won't group for shit. I'm lucky if I get 7 MOA out of it at 100 yards. I've tried 100 rounds of my friends reloads, LC M855, Fiocchi Match, Wolf Gold, and a Winchester White Box. They all shoot like shit. I don't think it's me, my friend has a similar rifle, but with a GI trigger, and I group sub MOA with his rifle... with next to no trigger time behind it. Hell, I get better results with my Ruger American Rimfire.

I assembled this rifle from scratch and I'm confident that the barrel nut is on right and the scope is torqued properly. All witness marks are still aligned. I had some clearance issues with the gas block and the CMR rail, but I fixed it and have ~2mm of space, which should be plenty.

Anything I can start checking/trying before I disassemble this thing and try it again? I'd expect much better results from this barrel.

[Failure2Stop]

If you seriously want to have it diagnosed, you can send the upper to me. I can do a safety inspection, test fire, diagnostic, and corrective action; all recorded.

Sincerely, let me know.

[ALCOAR]

The rifle's parts, and configuration should definitely yield accurate results.

If the barrel install was done successfully as you stated, then really the only thing that jumps immediately out is making sure you didn't over torque your muzzle device on when installing.

The ammo you listed that you tried isn't the greatest at all for precision/accuracy testing. That ammo most likely isn't capable of sub MOA or close to it especially with stuff like m855(10rd groups).

Get some true match grade ammo...Hornady 55gr. Vmax is my personal "control" for 100yds.

Obviously I'd be inspecting my crown, and inside of the barrel as thorough as possible as well.

[T2C]

I agree with Trident82. Hornady 55g VMax should shoot really well. Hornady 68g match ammunition should also perform well.

Over-torqueing the muzzle device will have an adverse effect on accuracy. Muzzle devices on my high power rifles are screwed on hand tight and kept in place with Loctite Blue. On any other rifle, I torque the muzzle device on at the low end of the specified torque range.

What kind of groups does your friend shoot with your rifle?

[BufordTJustice]

OP, spend the coin and take failure to stop up on his offer. Seriously. Like, right now.

EDIT: With no offense toward Trident, who gives solid advice.

[GH41]

Is the hardware used to mount the bi-pod touching the gas block? If not try it without the flash hider and then try another scope.

[netchemica]

I agree with Trident82. Hornady 55g VMax should shoot really well. Hornady 68g match ammunition should also perform well.

Over-torqueing the muzzle device will have an adverse effect on accuracy. Muzzle devices on my high power rifles are screwed on hand tight and kept in place with Loctite Blue. On any other rifle, I torque the muzzle device on at the low end of the specified torque range.

What kind of groups does your friend shoot with your rifle?

I'm not sure if it's over torqued or not. I'll take it off and out it on hand tight, the flash hider is designed to tighten itself during normal use, so I'm not too worried about it coming off.

My buddy never shot for groups, we have a ?10"? gong at 600 yards that we were shooting at. He can hit it 9/10 times with some cheap match ammo.

Is the hardware used to mount the bi-pod touching the gas block? If not try it without the flash hider and then try another scope.

I haven't checked that, I'll take a look when I get home.

[netchemica]

If you seriously want to have it diagnosed, you can send the upper to me. I can do a safety inspection, test fire, diagnostic, and corrective action; all recorded.

Sincerely, let me know.

PM sent

[556BlackRifle]

How much clearance does your gas block have inside the handguard with the bipod attached? Could be shadows but it looks like you might have a barrel harmonics issue.

[Ned Christiansen]

Some good suggestions.

Make sure your LaRue mount is not partly on the rail and partly on the upper. I always want that to work but.... nope.