Zootshooting

Yeg, modifying a magazine to fit the Kahr 1927's requires altering the hole for the magazine catch--the simpler fix is swapping the standard part out for a GI-spec one. There's actually very little in common between the closed-bolt 1927 of today with the original open-bolt 1927 and its select-fire 1921 and 1928 relatives... mainly because to be legal as a Title I firearm without NFA restrictions and stay legally sellable after the 1986 MG registry closure, it had to be "not readily convertible" to full-auto.

Trivial note, this is also why original 1927s have little collector demand or value... they're legally treated as machine guns (since they were converted from 1921s and still fire from an open bolt), but don't have the rock-and-roll capability of a true full-auto unless you convert it back to 1921 or '28 spec. (Which devalues it even further since it's no longer "original"...)

Today's Kahr built Tommys use either a slightly elongated hole in the magazine itself, or you will need to modify the mag catch itself. I have a bunch of modified mags so I didn't do the mag catch on mine. If you do the mod to the catch, you can use original mags.