1 piece scope mount bridging the upper/rail

[markm]

I have this cat's gun that is 100% primo build... Nothing jookie in any part of it...

He's been fighting the accuracy for a while, I'm talking 3 MOA with a good barrel and match ammo.... with some of the rounds grouping well and some whacked out fliers that don't make sense.

So I agreed to take this thing all the way down and figger this out....

I go to take off the Nightforce in a LaRue, NON-cantilever style mount and its half on the upper and half on the Geissele rail. I stopped right there.

Could that be the issue? None of those parts are loose, but It just seems like that's not good.

[Dano5326]

Yes, and Yes.

Also a few ideas...

FF rails are meant to isolate barrel from hand-guard movement. Handguards move whether FF or not.

Split on upper and rail may have also put recoil lugs, on mount, in poor position.

Split ring Larue mounts, SPR, need be tightened according to directions. The OBR type, top/bottom clamshell, are a bit more forgiving, but check for even space and torque.

I would also recheck barrel nut torque. On and off a few times to ensure contact surfaces mated well enough & torque spec'd.

I had a .75moa/10 shot recce go to 4+moa.. FFrail nut loosened.

Carbon or crap torqued muzzle device also a frequent culprit.

[markm]

It has to be right? It's behaving like a loose scope.

Thanks, Dano.

[davidjinks]

I "experimented" doing the same thing with one of my rifles.

LaRue 104 mount and NF 1-4x24 on a 16" upper with a DD RIS II rail.

Needless to say that experiment failed. My best group was 4 inches, around my POA. I'd get one maybe two rounds POA/POI but that was it.

Adjusted the mount so it doesn't bridge the gap and everything was straight and true.

[markm]

Awesome. This should be a simple solution.

I'm going to start with the mount before disassembling anything else.

[Iraqgunz]

There is no doubt in my mind. Especially since we know that there is flexing of the upper.

[markm]

Cool. Will be very interesting to see the difference.

[Magic_Salad0892]

I'd clean out the muzzle device and threads anyway, just to be sure.

[Failure2Stop]

I am inclined to agree with Dano, though I am curious as to how many rounds have gone through the gun, and if it ever shot to expectation.

[markm]

I am inclined to agree with Dano, though I am curious as to how many rounds have gone through the gun, and if it ever shot to expectation.

This gun has maybe 200-500 rounds... it has, on occassion shot near MOA. The odd timing of when it'd happen would lead us to believe it fouled in with a powder it liked.... then the next time he'd bring it out... 2-3 MOA or worse.

It's a Noveske SS barrel... I just never noticed the mount scenario until I'd set up to take the gun apart. I'll post Saturday's findings with Mount reposition only.