Stoner Mags issues

[Luvall]

I acquired 3 steel AR Stoner 20? round mags. One functions fine but 2 of them jam on the second round. Any suggestions on how to fix this issue?

[VASCAR2]

AR Stoner used to sell rebranded ASC mags. Not uncommon for the feed lips to be bent down to far. When loaded the bullet needs to set in a nose up attitude. Many times a faulty mag may feed flawlessly from one side and commonly fail to feed from the other side (dual feed mags). I use a pair of needle nose pliers to gently bend the feed lip up on the troublesome side to match the good side.

If the mag fails to feed from both sides I'd tweak the feed lips a little so the bullet nose had an upward attitude. This releases the cartridge so the nose of the bullet rises as the bolt pushes the rear of the cartridge forward. If the bullets lay flat/horizontal and are pushed forward the bullet get jammed into the mag well or barrel extension. This can break the tip off polymer bullets and cause the bullet to be deep seated. If you adjust the feed lips with needle nose pliers go slow and test the feeding after slight adjustments. A little tweak really works. Brownell's even sells a tool made to adjust feed lips.