In Murderer's Row, he has a shrouded-hammer 38, because he comments on the purpose of the shroud as he's threatening another guy.
In that impersonation, up in the Pacific North-wet (don't recall the book's title), it is referred to as a "sawed off Colt 357", but no mention of whether it's a Python, Lawman or Trooper. Or, for that matter, New Service or SAA.
Hamilton (who I loved to read, by the way) most definitely had opinions. The 38 Special was an extremely powerful cartridge. One spy - Nicholas - had an MO of carrying "extremely large, power handguns". Like a 1911, and a Browning Hi Power (although in that book he was using a model 29). The 357 was so powerful a "hand cannon" that Helm was betting his life that the other guy, if he had ever fired the gun, had developed a severe flinch from the recoil, and would miss if shooting Matt. In that same book he poo-poos the assassin's henchmen's guns as "nothing movie cowboy guns, nice for putting under your leg on a saddle, but not good for any distance", while the assassin had a 7mm Remington Magnum, that he could kill with hundreds of yards away. When he went to protect his ex-wife from threats, he found her new step-son was also armed with a "little nothing Lone Ranger carbine".
He did have some real good thoughts, though. Like how a gun was NOT a magic wand, and waving it around while chanting incantations like, "Drop your gun", "Stop or I'll shoot" and "Don't move" doesn't work in real life. Like Tuco the Rat said, "If you're gonna shoot, shoot. Don't talk." And "why use a gun if you are going to get in knife-range?" And my personal favorite, "Call him 'sir', and show respect. Makes him feel better, and does not make him one bit more bulletproof".