There is no way a 32 short colt will ever hurt your gun. It is FAR too low pressure of a round, and the Nagant is much more over built than it gets credit for.
The issue is lead shaving. Nagant cartridges are heavily tapered, while other 32 caliber cartridges are not. Thus they are very sloppy in a Nagant chamber. The shorter the brass, the more sloppy it will be.
Basically, there is no way a 32 short Colt is ever going to hit the forcing cone properly. It will always be off center, or slightly yawed - thus it will shave down or partially 'splatter' when it exits the cylinder. That lead has to go somewhere, and that somewhere is usually out of the cylinder gap, at 90* to each side of the shooter.
Dangerous for the gun? NO.
Dangerous for you and bystanders? YES.