U.S. Marshals Teddy Daniels (Leonardo DiCaprio) and Chuck Aule (Mark Ruffalo) carry Smith & Wesson M&P revolvers as their sidearms. Teddy's gun is a four inch Smith & Wesson M&P, with incorrect non-diamond Magna grips.
Could this not be a Colt model revolver, perhaps a Marshal (at least for this shot), as it appears to match its grip. Later in the movie, his service sidearm does appear to be Smith and Wesson Military and Police revolver, as it appears to have a ejector rod shroud. It is hard to say even having seen the movie personally, as the firearm is not present through most of the movie and when it is featured, it is only very quick, rapidly moving shots.SAWGunner89 00:09, 16 March 2010 (UTC)
the shot of the revolver in the holster is most likely a colt detective special in .38 special. but possibly a colt agent as they can't be told by the grip alone.
M1903 Springfield
Shutter Island prison guards are armed with M1903 Springfield rifles. Teddy Daniels also is seen with one.
Walther PP
The Nazi commandant uses a nickel plated Walther PP to commit suicide in the concentration camp flashback; Teddy Daniels (Leonardo DiCaprio) moves it away from the commandant to prolong his death.
The filmmakers selected the nickel plated model due to the way it contrasted with the wood floor of the office despite being historically inaccurate that back during WWII nickel plated Walthers did not exist yet.
M1 Carbine
Some of the U.S. Army troops entering the concentration camp in the flashbacks are armed with M1 Carbines.
M1 Garand
In the flashbacks to Dachau concentration camp, Teddy Daniels (Leonardo DiCaprio) and some U.S. soldiers are armed with M1 Garand rifles.