Following the wedding when the men get ready to go hunting, Stan (John Cazale) is seen pulling his Smith & Wesson Model 10 snub. What appears to a different firearm is seen from the latter part of the movie. See the quote in the fourth screencap.
Axel takes a Smith & Wesson Model 10 revolver with 2" barrel out of Stan's waistband to show Michael. Later in the hunting cabin Stan threatens Axel with it, and Michael takes it from him and puts one round in the cyclinder, clicking it empty against Stan's head.
Error creating thumbnail: File missingAxel holding Stan's nickel Model 10 revolver. Not sure if this is the same revolver Stan had in the first part of the movie. Michael - "What's that for?" Stan - "The same thing the other one was for." So, according to this quote, it's a different gun.Error creating thumbnail: File missingStan points his loaded nickel Model 10 revolver at Axel with the hammer cocked. That's not a very nice thing to do to your friend.Error creating thumbnail: File missingMichael unloads Stan's nickel Model 10 revolver, proving it was loaded whereas Stan claimed it was unloaded.Error creating thumbnail: File missingMichael puts one round in Stan's nickel Model 10 revolver leaving 5 empty chambers. "You want to play games? Alright, I'll play your fucking games."Error creating thumbnail: File missingMichael puts Stan's nickel Model 10 revolver to his head, clicking the gun empty on him. "How do you feel now? Huh? HUH? BIGSHOT?"
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(Trivia: DeNiro requested a live bullet to be used in this scene to heighten the sense of danger. John Cazale, who played Stan, did not protest, yet compulsively and understandably checked that the bullet was not next in the chamber for the scene.)
Smith & Wesson M&P
The Viet Cong soldiers order the POW's to play Russian Roulette with a Smith & Wesson M&P revolver. Michael (Robert De Niro) notably uses it when he asks the Vietnamese soldiers to load three bullets in the gun, which he then uses to kill three soldiers and uses their weapons to dispatch the rest. It's identified as a Pre-Model 10 M&P from its hammer configuration. That is what is known as a "Long-Action" M&P. The "Long Action" was phased out in 1948. Smith & Wesson did not start numbering the models until 1957. By then the "Short Action" with the re-designed hammer was standard on all models.
M16A1 rifles are carried by Nick (Christopher Walken) and Steven (John Savage) while serving in Vietnam. Michael (Robert De Niro) notabley uses one to shoot a Vietnamese soldier after hitting him with a flamethrower. Many soldiers carry them as well when Michael returns to Saigon to look for Nick.
Norinco Type 56 rifles are used by the Vietcong. Michael (Robert De Niro) and Nick (Christopher Walken) both take one from them during the Russian Roulette scene and use them to dispatch them all.
