How do you tell .45cal Colt from .45cal Long Colt? Without looking at the ammo? It could have been chambered in another caliber, too. Whomever handled it would leave prints, although SFB Baldwin may have destroyed them.
How hard is it to bring bullets that the gun is likely chambered for, and load the correct one while you’re pulling your little union trick? You might have even had opportunity to handle it, previously, and know.
They set a trap that killed someone, and Baldwin was stupid enough to set it off. Murder.
If anyone, using their own weapon, tried to claim that they didn’t load it with real bullets, I would need serious convincing to believe them. In this case, I find it highly UNLIKELY that Baldwin loaded this weapon.
Whoever did is a murderer, and the police seem to want him to get away.