So I finished putting my AR lower together and stuck a mag in for functionality of the mag release. I have 3 30rd mags...one thats ancient that I got from my brother when he got out of the Army in 93-ish and is an OKay. It fits great and drops fine. The other two are Center Industries new in package that I acquired while on active duty. These mags fit extremely tight and require a lot of effort to pull them out. Just out of spec? The problem seems to be on the backside (think primer end). Anyone else had this problem?