LaRue tOBR ammo problems

[bfk4lyfe]

My 16" tOBR came with a .4xx 3 round test target with 168 FGMM and I'm able to consistently shoot give or take .75 5 round groups with the same ammo. BUT it won't shoot anything else worth a damn. 175 FGMM 2+ inches, 168 AMAX 2 inches, 168 ELD-M 1.5 inch, 178 ELD-X 1 " (acceptable I suppose), and various 155/168/175 hand loads are all around 1.5+. My AI AT is able to shoot all these sub 3/4, so the ammo is good.

Has anyone heard of or experienced this themselves?

Am I fussing over nothing? At the end of the day I guess its not a huge problem since the 168 FGMM is the cheapest match ammo out there, but I'm trying to find something with better ballistics.

[mgrs]

Interesting you post this as I was about to ask about this on TOS or call the MFG for advice about the same...

My new tOBR (built late last year) 7.62 came with a .69 test target with 168 fgmm and I cannot get it to group less than 1" 5 round groups with 168 fgmm, 175 fgmm, or multiple handloads with heavy bullets. With FGMM and 5 round groups, I average 1.5-2 moa.

Working up a load with IMR3031 and Hornady 125 SSTs, I can get consistent .5-.7 moa out of it. Most everything with heavy bullets is 1-2 moa. I did find a very heavy load with 168gr smks and 2000mr that shot well ( better than factory FGMM) in the rifle, but the brass looked like it was too much pressure for an auto loader.

Before the next time it is fired, I have considered re-torquing the barrel nut and removing the muzzle device to see if the former is loose or the latter is affecting the harmonics. Otherwise I am at a loss. Sold another AR10 that I was able to shoot much better to get this rifle.