I have always read/heard that the AK top cover is too unstable to mount sights and or optics. Yet, the Galil seems to have solved this problem since no one complains. I have an original IMI Galil ARM and I never noticed and shifting in POI due to the rear sight being located on the top cover. Also, all the "Krinks" have their rear irons on the top cover and I havnt heard any complaints, although I hear very little accuracy evaluations from such guns.
The other day I was shooting my ZPAP M85 pistol (with the hinged top cover mounted optics rail and rear sight) and was getting some crazy POI shifting of up to 10MOA with both Aimpoint and open sights. I was freaking out. I thought my Aimpoint busted lose but then when using just open sights, it was also doing the crazy shift in POI.
I'm not sure if I closed the top cover wrong since it seemed rock solid as usual with zero play. Maybe something is "breaking in" on this fairly new gun or maybe I'm having a stroke.
I went back yesterday to try and repeat the problem but couldnt. I'd fire a group then open the top cover, remove the main spring, move the bolt back n forth then put everything back...then fire another group. I could not discern any major POI shift that I wouldnt normally get using irons or RDS with my old eyes (my best groups are 2MOA but typically run around 3.5-4MOA with good ammo). I did this at 50 and 100 yards. Now, I'm also very careful to check the top cover to make sure it is locked in proper and tight. There seems to be 5 points it locks in:
The front hinge which moves freely to open and close the cover,
The rear where it mates up with the mainspring detent that pokes out the hole in the rear of the top cover,
Both sides of the top cover in relation to the receiver,
The front left side where the bottom of the top-cover mates into a matching recess in the front trunion's left arm (not sure if this is all models or just a nice feature on the ZPAP).
So my question is: Does anyone else check the accuracy of their AK pistols? Have you noticed any POI shifting after opening and closing the top cover (to add oil or clean the gun)?