Well, heck! Isn’t that what NASA is for, to determine answers via experiment? I propose a national contest! We need to pick 2 volunteers to go up and fight it out. Naturally, to make this a “real” scientific experiment, we’ll need several pairs, one for each caliber of handgun, a pair for each caliber rifle, shotgun, etc. This could really kick the economy out of the recession, a la the way the moonshot did way back when. Reactivation and further development of the space station to provide a big enough lab . . . .
In a zero-gravity fight in space (no walls to grab) things get hairy. The recoil against one shoulder would put you into a spin that would require some kind of propulsion to correct. A pistol would do the same thing unless fired from your center with both hands.
In some sci-fi story I read and forgot everything else, Space Marines dealt with this by mounting their rifles onto the center of the chest of their spacesuits.
In one of Larry Niven’s scifi novels, a single rifle shot was used by the solo operator of a spaceship in a solar orbit to take out a pursuing spaceship. He shot from outside his ship, in a space suit, magnetically attached to his ship, IIRC. Remington 700 with a good scope, I think.
The target was something like one quarter solar orbit away. The neat part was that the shooter did the orbital calculations necessary to intersect his bullet’s trajectory and the orbit of the target ship in his head.
No, Mythbusters totally de-bunked that one. Shoot a hole in a light air tank with 15 or fewer psi and it will go “ffffffffffff” with very little other consequences. They did it with a jet fuselage, but a spacecraft wouldn’t be much different except for a few pounds more pressure difference. Your main concern would be loss of air supply over the long haul, so stick some chewing gum in the hole or something.
Anyway; that was a refreshiung write-up. Correct and not stupid or ignorant. That’s pretty rare.