One comment on follower profiles not really covered here is the feeding of the last round especially as applies to large rounds. I have found that relieving the ridge in the follower about half way from the front allows the last round to more easily come up under the extractor and feed it smoother. Not my idea but was showed to me by David Miller. There is an excellant series on the AR forum about proper mods for proper feeding done by Duane Weibe with excellant pictures explaining each step. Worth reading for anyone having feeding concerns.