Great theory - except that it won't quite work, as at least for the GA Arms 100gr .32 H&RM ammo, the case bulges just ahead of the rim - maybe 1/3 the way up - and not symmetrically - remember, the Nagant chambers are slightly tapered, a la the M1 Carbine. The Magtech .32 S&WL's occasionally split, too.
I chrono-ed those rounds in a 'proper' .32 Mag - the Ruger BHG SS Single Six I recently bought. The Magtech's are fine, but only make 644 +/-22 fps, while the GA Arms H&RM's made 1,117 +/-17 fps - and bulged in the Ruger! They were also, as in the Nagants, excessively nasty - rendering the ejector of the SSM fouled after one cylinderful. While the .334" OD Magtech ammo cases did not appreciably swell during use, the somewhat smaller Starline .32 H&RM cases swelled from 0.333-.334" initially to the chamber's 0.337" ID - generally in the same spot as from the Nagant chambers, just not so much. Good safety glasses are a must here, it spits nearly like the Nagants with that ammo. While the S&WL's fell out, the GA Arms .32 H&RM's needed help - and, recall that the SA ejector rod was useless after the first cylinderful. Perhaps the Starline .32M brass was sized a bit small - hopefully, by GA Arms, rather than Starline. It's easy to re-size brass a bit smaller in OD... the reverse, is a problem! I love everything else I have ever bought from GA Arms, but these rounds are gorrid, IMHO.
I still feel that the .32-20 cases and the Lee Nagant dies, with 100gr LDEWC or 83gr DEWC's, makes the most sense - if you have to reload. We need a realistically priced Fiocchi ammo equivalent...
Stainz
PS I pulled apart several of the Magtechs and GA Arms rounds to find 2.3gr of a sphere-like propellant in the former, and a whopping 8.7gr of a fine dark grey dust-like mess in the latter... that's a lot of powder!