Actually the only other small arms that had them for use was the 03 series. That was because the clip fit the top of the receiver and already existed. The carbine had no such cut, thus needed an external loader for use with magazines.

The BAR, which used the 03 stripper clip, did not have its magazine loader standardized until very late, circa mid 1945.

Thus the carbine stripper clip and loader were under development after the war ended.

The SMG's never had stripper clips developed but the M3 series did have a loader to aid in loading .45 ammo against a very strong magazine follower. The M3A1 had the loader as part of its wire stock.

The Thompson never had stripper clips, nor a loader.