Have to re-zero every range trip
i have a noveske chainsaw lower, and what i was told is a BCM upper with DD mid length barrel. i bought the upper used off this forum. optic is a new aimpoint PRO. ive found that i have to re-zero the gun nearly EVERY single time i shoot it. this last time, it was over 1.5ft left at 100yds, previously being zeroed dead on at 50yds. doesnt matter if it was a training day, or static 50/100yd range.
after shooting, all i do is clean it, and store it. it doesnt get knocked around, and the LaRue quick detach mount is solid and tight. the dot is screwed in tight to the mount. weird thing is, i had the same problem with a previous upper, and a different aimpoint.
the ammo can either be the exact same, or something different entirely, and i get the same results. im NOT that bad a shot, and it seems strange that with quality parts and sights, and the same ammo, its off by at least 18in at 100yrds. any ideas what it could be.