I have carried three, 8-round mag's with my Springfield Armory 1911A1 for a little over 15 years. During most of that time, the mag's were loaded, though I was always careful to "down-load" them by one round when not actually carrying the pistol. During a recent trip to the range, all three mag's failed to lock the slide to the rear after the pistol had fired its last round. This happened even when slowly hand cycling the empty pistol. I was very skeptical that all three mag's would "give up the ghost" at the same time. When I got home, I disassembled the mags to make sure I hadn't improperly assembled them during the last cleaning and everything checked out. Then, I checked the pistol with an 8 round Shooting Star mag' and a couple of 7 round G.I. mag's (All of which have steel followers) and the slide locked to the rear perfectly for all of these mag's. It should be noted that the Shooting Star mag' is just as old as the Wilson mag's and had also been stored with at least a few rounds in it. I am convinced that the weakness of the Wilson mag' is not in the mag's spring but in its polymer follower. I did order new mag' springs & followers for the Wilson mag's but I think I'm going to replace them, over time, with all steel, 8-round Chip McCormick magazines.