I am shooting in the dark here, but I do have a pair of Uberti '51 conversions. They are marked for .38 long Colt and .38 Special. I use .38 Spl ammo with .358 bullets.
Before going any further, check a few things on your revolver;
- is it marked for .38 Spl? If it is - there's your answer. If not continue to the next two steps.
- are the chambers in the cylinder stepped, or bored straight through?
- slug the barrel to see if it is bored for .358 bullets, or .375?
The answers will determine what ammo it will take.
If the chambers are bored straight through to a .375 barrel it will need .38LC cases and heeled .375 bullets or soft hollow based .358 bullets. If it has stepped chambers to a .357 barrel and the cylinder is not too long it should take .38 Special ammo.
Case lengths for .38 Special is 1.16". .38LC is just a bit shorter at 1.03". .38 Short Colt was a copy of the .380 Revolver designed for Webley revolvers in England, and the case is .70" I wouldn't think you would want to bother with the .38 Short Colt.
This is my offering. If anyone has more knowledge & experience, please chime in.
As .38 Special cases fit, and blanks do not have a solid projectile, I see no hindrance to using .38 Spl blanks, except for any possible confusion it might cause.