Wanted to post an update on my Mako mags. I have 20rd, 30rd, and 40rd mags from them. When seating the mag, all it needs is a firm pull up to lock it in. These are not like other cheap ****ty mags... Do not bang or slap them in after seating! If you do- you will have all kinds of feed problems. Smacking them in seats them to deep. The first round my load, but randomly through the entire mag the round will jam on the ramp. I ran through close to 400 rounds sunday at 100% flawless operating loading w/ a firm upward pull. I do load on an open bolt also. The 40rd mags are not obtrusive or hinder the use in any way that I felt.