All the MS rifles in those calibers have a cartridge control ring as part of the magazine which hold the cartridges parallel to the follower. The early models don't have this and rely on the correct COL to keep the cartridge from tipping as the bullet nose is controlled in a shaped recess at the front of the magazine. On the later rifles this recess is absent as the cartridge is held in the correct position by the cartridge guide ring so bullet COL and or bullet shape is not important.

Matt.