The SPORTER marked magazines appear to have been a produced between the early one that did not have any model information on them and the ones stamped 23A & NRA MATCH. I have seen the SPORTER versions with both the early and late type follower - all also have been stamped 22 LONG RIFLE (the early ones were stamped 22 S, L & LR).
I have found that even magazines that are stamped the same can vary, basically the rib on the rear is slighly different in length (at the bottom). There was an instruction sheet put out by Savage about fitting these magazines to a 23A, it involved filing the bottom of the rib.
