I've been using mags with split metal followers in my Commander, and have seen no signs of the damage that others have reported. I've used G.I. followers, rounded followers, and Shooting Stars, with no problems. Metalform makes a metal follower with a "skirt" that prevents the follower from moving forward beyond the confines of the mag tube, and you might try those. I was going to get them for my Commander, until I found the split followers were working OK. But, if you want plastic, try the follower/spring kits sold by Wilson Combat; they're intended for Officer's length mags, but fiddling with spring length should give you a 6-rounder that works.