DESCRIPTION
The reason the PX-57 mag only holds 20 is the longer rear leg on the follower. Design is fairly close. The Mag body on the PX57 is designed like the FSN where it juts/bulges out around the mag release cutout. They will not fit in the Rock. Cutting the leg allows 24 but then is allowing the follower to tilt too much, so definitely don't do that..