In Blood Meridian, Cormac McCarthy references the "Whitneyville Colt" horse pistols with which the scalp hunting party is outfitted. One of the characters also carries one of "Colt's five shot belt pistols." No maker is specified for the rifle that the leader, John Joel Glanton, carried but was referenced as a swivelbore, which was a concept I had to look up. The operation is fairly well laid out in the text, I just never knew such a thing existed.
In No Country For Old Men, the rifle Moss uses to hunt pronghorn in the beginning was described as "a heavy barreled .270 on a '98 Mauser action with a laminated stock of maple and walnut." The description of him cocking the hammer on the pump shotgun later in the novel is what tipped off the armorer for the film to the fact that it was a Winchester '97 (per the imfdb/DVD commentary track.) Also Sheriff Bell states that he "still likes the old Colt's .44-40." Says that if shooting somebody with it doesn't work, you can just throw it at them. Later in the novel, he opens the gate to check the load. In the movie, he carried a 1911 though.
I'll try and look up or remember more tomorrow.
Just came to me. In the Gabriel Garcia-Marquez novella In Evil Hour, the gun references were fairly vague. "Jaguar gun," "long barreled .38" and such. When rifles are distributed to a makeshift posse/militia, one of the townspeople shows off his and explains knowingly to one of the others: "it's a Madeinusa." I found that to be particularly humorous.