Guessing just errors.
I read a lot and find gun errors annoying. Recent goofs run across include the Marines using Garland rifles in Korea, a detective using a Takarov pistol, someone leaving a Glock with the safety off, someone loading a Beretta 92 14 shot magazine, someone using a Browning HP with 14 shot magazine, a character in one chapter using a shotgun which somehow turns into a 98k two chapters later etc.