When people hype the use of the wrong ammo in Nagant revolvers they always seem to leave a few points unsaid. Like the point that .32 S&W, .32 S&W long and .32 H&R magnum ammo is hardly more widly avalilable than the 7.62 Nagant ammo and generally those "alternatives" cost more than proper 7.62 Nagant ammo. The larger point left unsaid is that while those substitutes may go bang you can't expect ever half-assed accuracy. The Nagant revolver and its ammo are designed to work together as a system. The 38 mm long cartridge case extends out the front of the cylinder and enteres a recess in the rear of the bore. It not only serves as the gas seal, which is the whole point of the Nagant design, but it also serves to guide the bullet straight and centered into the bore. The Nagant chamber is cut large enough to accomodate both the bullet and the surrounding cartridge brass. Take away the brass, as when firing a shorter case, and the bullet is left to wobble unguided through a chamber some .020"-.030" larger than bullet diameter with nothing to keep it running straight and centered before it slams into the bore, which has no forcing cone to help center up a cockeyed bullet.
The Nagant can be a fine, light weight and accurate small game gun but only with proper ammo. I've been working with handloads for my Nagant and have been getting groups of 1.5"-3.0" at 25 yards, none of those "alternative cartridges" will do that well at 25 FEET! Firing the wrong ammo just because you can is really not very bright. One can, for example, fire 25/35, 30/30, 32 Winchester special, 32/40, 38/55, .375 Winchester and 44/40 rifle rounds from a .410 shotgun. But is there ever a good reason to do that?