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Topic: Weird accuracy problem  (Read 286 times) previous topic - next topic

Weird accuracy problem

Aero Precision M5 upper and lower. Criterion and Oden Works barrels have the same issue. I get 2 groups 2 inches apart depending on what side of the mag it feeds from. Each group would be a 1/2 or less on their own. Tried multiple brands of magazines, swaped complete lower from my 308 build. Also swaped bolt and carrier, scope and mount, buffer and spring. Anyone else have this issue? Thinking about trying a new  upper next. All barrels passed the go/nogo gauges. Both factory and reloads shoot similar.

 

Re: Weird accuracy problem

Reply #1
Although it sounds like every other round seems to point to the magazine stack but I'm thinking the barrel's shifting in the upper receiver or the entire upper assembly is moving.

When I install a new barrel, I measure the bushing and the receiver opening then wrap with the appropriate thickness stainless steel shim to obtain a "snug" fit. I also pre-torque the barrel nut several times, back off then torque to 45 to 50 ft pounds. Also, addressing the pivot pin and side to side play in the rear lug helps too!
Why are there more than male or female genders listed?