Sarge:
Just for interest: I have a Martini Cadet re-chambered to .32-40 using the original .310 Cadet barrel. Case length is 2.13" and it fits just fine. The twist rate is not really high enough to stabilize the slow 165gr factory-load, but 150gr 8mm bullets swaged down a few thou and revved up a bit are straight shooters. This was a common conversion in the NT many years ago when a ban existed on high-velocity cartridges:- a .310 cartridge could still be chambered and fired to satisfy a curious copper!

...and a friend has a Cadet fitted with a Ruger Mini-Thirty barrel (.308 cal) chambered for the .30-30 and it safely shoots and ejects Winchester factory loads all day long.

Nothing to add regarding the .38 cal chamberings though, sorry....