This is a problem, for some reason, with the .22 tube-feds. If you can't get one from Gun Parts/Numrich, Brownell's has had one-size-fits-all kits, over-length, trim(carefully) to fit. You'll need to figure out what follower you need, there are a lot of different types. You could also buy one for a 39A and shorten that, you'd have to make sure the knob correctly engages the outer tube. There's a tiny flush pin that holds the knob on, knock that out, remove knob and guts, shorten the inner tube, use a pin vise to drill the pin hole and reassemble. Unlike the early Marlin .22 magazines, the industry has pretty much standardized on the diameters of under-barrel .22 tubes, so a universal tube kit can be had.Have an old 1978 39M Inner magazine was lost years ago having trouble finding one. Anyone know a good place?
Thats the ticket!! Descent price too for a reproduction. Ebay also has originals for the pre1975 39A's in the same price range.