Billy was a real gun nut. George Coe said that he was either shooting his pistol or cleaning it. He owned several pistols. We can see from the Upham photo that he carried a Colt SAA. He hood winked old Patre Pollack out of a Colt Lightening, a .38 Long Colt. That pistol was confiscated from him when he was arrested. He probably lost a Winchester too. Not long before he died someone loaned him a Colt Thunderer, which was like the Lightening only a 41 caliber. If he was carrying a pistol the night he was killed that was probably the one. There is a photo of him holding a very nice Winchester '73 3/4 magazine rifle that he probably took from Pete Maxwell. Willi Chisum said "If the kid wanted anything he just took it." Well, that's probably right.
Those early DA Colts were popular. Pat Garrett carried one, but he probably killed the kid with a standard Colt SAA...I've read it was a 44/40. They were brand new in that caliber when the kid was killed. Most were 45's, but they didn't make the 73 Winchester in 45 Colt in those days, so Colt started making their SAA in 44/40 sso the rounds would fit the rifle.
George Coe, who lived until 1941 said that he was a better rifle shot than the kid was, but that the kid was better with a pistol. He probably was. Coe also said that the kid never cared much about money except to buy cartridges with. Shells in those days were expensive costing fifty cents a box or half a day's wages. (The kid, however" said he was owned $4 a day when he worked for Tunstall and Chisum.) Billy never had much of value. His horse, maybe his watch and the clothes on his back. Coe, however said that if there was a "clean shirt in town, it was on the Kid's back".