i recently purchased a eotech holo site for my mini 14 eotech item # is 551.a65 it is a higher end model. i bought a aimtech piccatiny rail to replace heat gaurd and allow for forward mounting. so i go to the range and zero the holo site in, its nice REAL nice my groups were maybe 2-3 inch on bullseye at 100 yards, so all was good worked great , next couple days i went to range again the f***ing thing was shooting off!! re zero it and switch to my m1a for a while i came back and tried shooting the mini again and it seemed to be off....its either that the mini14 wont hold zero which a guy at a gun store told me or the eotech is resetting everytime i turn it off, i cant fiure it out, i will go back to range and try mounting it on different guns to see if maybe the thing is just screwed. it also mite be the aimtech rail...who knows. i was curious if any one else has had problems getting a mini14 to hold zero, that is what the guy at the gun store tried to lead me to believe. i will post again after i have tried it on my socom16 maybe it is the mini?
Some of the Mini-14's are notoriously inaccurate, but I've never heard of a group changing because of the gun, unless you changed ammo or something. I'd lean towards something moving in the mounting system or a bad sight. Try removing the sight and shoot a few groups with iron sights from a rest and see what happens. BTW, welcome to G&G!
mini 14 holds zero?? 
