i took a AR class this past weekend and towards the very end of the class i had an issue with the magazine seating and secured in the magwell. I had run about 500 rounds through the gun that day and have no more than 700-750 total threw the gun, including that days round count. Towards the end if the class I started to notice that the PMAGS would not secure in the magwell if the bolt was closed. They will seat and secure if the bolt is locked to the rear. I also have a 2nd Amend mag and it will seat and secure in the magwell regardless of the bolt position. So what gives? Anyone experienced this before? Is it because the gun is dirty? I wouldn't consider a gun with less than a 1000 rounds through it, that dirty....please advise. FYI...... the gun is a KAC Mod2 SR-15