Quote Originally Posted by Daan Kemp View Post
Don't know about M14icon mags. FAL 30 round mags worked well but after some hundred rounds, the bullets made dimples in the front of the magazine from the inertia during firing. Caused cartridges to hang up and not feed. Quick taps with the hammer cured that, but it kept repeating. Of course, shooting hundreds of rounds per session might have been causing the dimples. Never had such a problem with the same number of rounds through 20 shot magazines, not enough inertia with the shorter mags.

During movement the length of the straight magazine also caught on lots of things if you weren't careful, and prone shooting didn't work.
The Mk1 Bren magazine had the same issue and if you can find a very rare Mk1 mag, they usually display dents to the front. The Mk2 mag (Or Moded Mk1*) had a an auxiliary spring at the front which stopped the forward movement of the rounds.