You also can use 32 H&R Mag and 32 S&W Long. I find the 32 H&R to be more accurate the the 32 S&W Long. and never had any bulging problems with the brass.
I tried the 32 ACP cylinder when i first got my Nagants. I never could get it to index w/o a hassle and ended up including it when I sold one of my Nagants. The Fiocchi ammo is pretty hot stuff (especially compared to the Russian yellow box) .
The olny issue in using 32 S&W Long or 32 H&R Mag ammo is that the cases might bulge since they have a slightly smaller circumference than the Nagant ammo. I've never had that problem and have had the 32 H&R Magnum brass reloaded and have used it in all 4 of my 32 H&R revolvers w/o any problems.