Mags are always a consumable item, but I have mags that are pretty rough shape that have been loaded for several years now and only 1 that Ive seen has had cracked feed lip by spine, and it was that way when I got it. It still works well. Ive got another that has the tab on the bottom plat torn off where it covers the spine, works well too. I only have 1 mag that doesn't work right and it got hit hard enough to move material on the side where it inserts into the mag well and takes significant force to get it in. Occasionally it has a fail to feed issue but still useable at the range