The MagPul Ranger Plates fit the Both the Stainless Steel and the aluminum Mags, with one issue.
On my Mags, the SS with Ranger Plates takes out some of the extra room for seating the mag into a closed bolt, BUT IT WILL STILL CLOSE WITH MINIMUAL PRESSURE. Much better than a standard USGI Mag loaded with 30 rounds.
The aluminum Mag however, just lets the last bullet fit in place with VERY LITTLE ROOM left. You should make sure you are comfortable with this situation, BEFORE you rely on it.
I tried the CProducts aluminum Mag in my weapons and they would still chamber a round with out problem.
I have only tried the 1 aluminum mag so far though.
I really like the CProducts SS Mag with Marlude. It has been inserted into a (Closed Bolt) Mag well over 100 times now It is showing minimal wear. It also seats easy on a closed bolt!
REMEMBER, Larry at CProducts has the NEW TaticalPul for the magazines. It looks to me like it uses less of a plate insert than the Magpul Ranger Plate, so it should take up less space inside the Mag wich would allow better seating, not that the seating is hard now with the Ranger Plates.