YOU need to be more specific by what you describe as a "PROP" gun.
Many prop guns are made up to look like real guns but can't be fired. Not even blanks. Some are made up from real firearms and will accept blanks. The frame of course on these remains functional and needs to be registered. Some have everything that moves welded into place and can or have been removed from the registry.
I bought a whole bunch of "PROP" guns from an auction in California appx 35 years ago. They weren't described as such and I wouldn't have expected them at a military surplus auction. Everything there was on a list with lot numbers or batch numbers. That was it, no more descriptions.
When I got the box open, it was full of what appeared to be 1911 Colt semi autos. Well, they were replicas, solid cast hard black rubber, impregnated with lead to give them the same weight as a real pistol. Apparently, the MPs weren't allowed to carry real firearms and were issued these instead. They made great clubs and from what I was told, they were used as such regularly.
So please, if you want your question answered properly ask the proper question, with a proper description of what you are selling.