FYI, I have another rifle that uses AR mags and follower color has never been a consideration. I have several aluminum/steel magazines that have green, a couple with orange followers and I have never had a magazine related problem. OTOH, I got an M&P-15 just before the shooting in Newtown happened last month and it came with Pmags. Before the the prices started to jump I got about a half dozen more ($12 each) since they came OEM with the rifle and the followers are black like the mags. They all seem to work okay in the other gun, but I now have the S&W and after reading a number of posts about green vs. orange vs. grey followers I was curious if it had to do with manufacturer code, mag capacity, design differences, or something else. So far I've shot a little over 100 rounds through various mags, mostly the Pmags, and they all seem to work fine.