It surprises me that no one has yet said..
"Hawgleg" = SA revolver
Just what are you kids reading/watching these days,that you missed that one???
some of the slang terms are historical, some are amusingly descriptive, some are even sarcastic. And some are just juvenile. Sometimes we know pretty well where the term originates, sometimes, we can only guess.
Two terms I put in the juvenile class are "shotty" - referring to any shotgun, and "Deagle" - referring to the Desert Eagle pistol. I'm unsure where "shotty" originated, but "DEagle" came from a video game which didn't have enough characters in its weapon name slot to write Desert Eagle, so the wrote DEagle.
Gat - probably comes from Gatling gun, and meant revolvers, due to the similarity of revolving parts. Also became used at a time when semi autos were not very common civilian guns, so by extension, used for all handguns.
Roscoe, and Heater are, like Gat, terms from the 20s/30s or possibly earlier.
Ma Deuce is the M2 .50 cal machine gun (not Duce)
And tis "combat Tupperware" a sarcastic reference to polymer frame pistols. Tupperware, (only) is something I use in my kitchen
"Bottom feeder" refers to semi auto pistols (where the magazine goes in from the bottom).
Wheelgun - revolver.."wheelies" -from the same kids who say "shotty"..
"the Mighty Mattel" - Vietnam era slang for the M16
Crank and Yank - SA revolver shooting
Spray and pray - unaimed rapid fire
"piece" most likely, originally comes from "piece of ordnance"
"mousegun" - small size, small caliber pistol
Racegun - heavily customized pistol used for competition shooting where speed is a factor.
"Bellygun" - short barrel pistol (usually revolver) meant for close range defense (belly to belly distance, etc.)
there are lots of them, most I can't think of, right now...
and then there are personal names for guns...
My first deer rifle, I nicknamed "Killdeer" after Hawkeye's gun in Last of the Mohicans... because, well, it DID!
Back in 1980, I got a Browning BDA .45. One of my friends took to calling it "Alice". Said the initials BDA stood for "Big Dirty Alice". I wasn't thrilled, but my wife found the name amusing, and ever since, that gun has been "Alice".
Works very well when needing to refer to the gun without others knowing. "have you seen Alice lately?" is our "code" for if I am carrying...