I just got the 10 round PRI mags in the mail the other day. Although they are obviously of higher quality than what I got with the STAG upper, I have noticed that its pretty hard to get them to lock into the mag well. But this is either only when there are 10 rounds in the magazine (Any less and it pops right in) or when the BC is forward with 10rounds in the mag, it also wont lock in easily. But when the BC is locked back (chamber is open) it loads fine. Ive tried this in two different STAG 6.8 uppers and both had the same problem. I tried the magazine that I got with the upper and it works perfectly fine. I can get the PRI's to seat properly but it takes a hell of a lot of force to get them to stay there. Any suggestions??