Update
As most people speculated/assessed, it was probably an assembly problem.
I tore down the carbine a few days ago, and immediately put it back together. I did the old "snug up three times" process, then set my wrench for 30 ft. lbs. and torqued. Not aligned for gas tube. Set the wrench to 40 ft. lbs., torqued, and it was aligned. Finished assembly.
I also tightened the mount/scope connection. It wasn't exactly loose, but would tighten about 1/8 turn.
Groups have shrunk by about 1/3rd (about 2" at 50 yards with a 1.5x ACOG and federal XM193). Groups with irons are the same (my usual). No wandering zero or shift in PoI.
It just goes to show that I need some more experience assisting others to do a build.
'That whole effort was held together by sweat, shame, and a tiny bit of pride.' -- Son of Commander Paisley
Bookmarks