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.

[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.

[rcoodyar15]

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.

I was going to ask about your scope mount.

I had a larue SPR. My gun was spraying them too. I torqued down the mount so tight I could hardly close the levers and have to use the sling to undo them. That is what it took to stop it moving around. I removed it and replaced it with a fixed mount.

[mtdawg169]

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.

This is one of the most awesome things I've seen here on M4C in a while. Nice move Jack.

[BufordTJustice]

This is one of the most awesome things I've seen here on M4C in a while. Nice move Jack.

It's sacrifices like this by members with serious real world knowledge (like Jack) that truly adds to this community.

[ryantx23]

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[Zim]

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I just finished installing a CMR, and the Noveske low profile gas block was definitely contacting the rail. I had to take a few whacks at it until it looked good, and it still might not have enough clearance. It's definitely a finicky rail when it comes to gas blocks.