Wouldn't that be the 320 rifle round? They were chambered for that and it is full cylinder length. You can make cases from 7.62 Nagant [pistol] brass. As I remember the bullet is .323.
.320 RR is same diameter Brass as .32 - 44 - it is not .380 in diameter.
I posted images comparing .32 - 44, .320 RR, and .38 - 44 earlier in this thread, if you would like to see what the .320 RR Cartridge looks like...and to compare it to .32 - 44, the images are in Post #31.
Bored Straight Through Chambers of .380 diameter, do not co-respond to any kind of known Cartridge, and certainly none having a Bullet of .321 diameter.