I’d be fine with that too.

I also did some digging.

Per the “Name Stability” policy you’re right that 1F52B will always have the name “Pistol”. That name was set in Unicode 6.0. However in Unicode 9.0 the aliases/annotations of “handgun, revolver” were added. These seem to be aliases, but not formal aliases since those have specific rules, so it’s not clear to me if they can be changed. There is also an identity policy, but how it might apply in this specific case is unclear.

I bring this up since other Emoji have similar aliases that are unclear. For example the “old key” emoji mentions “encryption”, the “dagger knife” emoji mentions “rated for violence” and “hate”, and the "lips* emoji mentions “rated for sex”.

As such it isn’t clear on identity. So is “water pistol” a valid interpretation of “pistol”? I still think not, but I think it’s a reasonable argument, even if that wasn’t the original intention.