6mm arc mag - Geissele 6mm ARC, 20 Rounds, Rifle Magazine

4 of 5 stars because they are so expensive and I've not done any long term testing; only about 300 rounds. I've tried close to all, if not all 6ARC mags available: all makes and sizes. I've found that several mags/brands work flawlessly for 12 rounds or less, but even then, it is an individual mag's personality. Geissele's (I now have three 20 rnd mags) are the only mags that I've had flawless running with! All three have worked perfectly for a collective 300 rounds.