[bitchtits]

Undo the two screws that hold the mag well in slightly until it locks in.

I have this same problem with my tanaka ltr. But only when the mag well is in the gun. If I remove the mag well they lock every time.

Im still not 100% sure what causes it as the mag doesn't make contact with anything on the rifle and this happens even when the bolts out.

 

[bitchtits]

Yeah there is slight play in the mag,its also like this with the long mags.
If i remember my AICS was the one with the least amount off movement.