Dean (Jensen Ackles) and John Winchester (Jeffrey Dean Morgan) are seen using a customized Colt M1911A1. 45 pistol throughout the series. The gun is seen having symbols along the side, the gun has ivory grips and is chromed.
Colt Patterson 1836 aka The Colt
The legendary revolver that can kill anything. Built by Samuel Colt himself for a hunter (although it's thought that he built it for himself). The night that Halley's Comet flew over head and the night that all the men died at the Alamo, Samuel Colt created this weapon, along with 13 silver cartridges. He carved a pentagram into the handle, engraved a quote from the 23rd Psalm, and a high priest blessed it.
The Colt is passed to John Winchester by Daniel Elkins along with five remaining cartridges of the original 13 (Dead Man's Blood). Cartridge 9 was used by John Winchester on vampire Luthor to save Sam Winchester's life ("Dead Man's Blood"); cartridge 10 was used by Sam shooting at the Yellow-Eyed Demon in baby Rose's nursery, but he missed ("Salvation"); cartridge 11 was used by Dean to kill Demon Tom who was beating Sam senseless ("Devil's Trap); cartridge 12 was used by Sam to shoot John in the leg after he'd been possessed by Azazel (The Yellow-Eyed Demon). John then traded the Colt in a deal with Azazel to save a dying Dean...but the Winchester's later re-gained the gun and Dean used the remaining cartridge to kill Azazel.
Later in the series, Dean is shown going back in time to 1973 where he steals the Colt to shoot at the YED in that time period (but he misses)--so, technically, that means Dean uses up cartridge number 8 of the original 13.
Afterwards, Bobby and Demon Ruby figure out how to make the gun kill demons once again. The gun was also used as the key to a gate to Hell in Wyoming, which was surrounded by churches built by Samuel Colt in the 1800's (which is a major reason why I think he was a hunter). Altough the gun can kill anything, it only has 5 shots, and has to be taken completely apart in order to reload the pistol.
In the fifth season episode "Abandon All Hope..." Dean uses the Colt to shoot Lucifer but it does not kill him. According to Lucifer there are five things in creation that the Colt cannot kill, him being one of them.
Used by mother-figure Ellen, who under demon control pointed at her own head.
Single Action Army Artillery Revolver
Bobby Singer (Jim Beaver) carries a Single Action Army with 5.5" barrel and wood grips. It's lack of a 4th frame screw strongly hints that it is either a Cimarron or Uberti.
Walther PPK/S
Used mainly by Bela.
Glock 17
Used by FBI agents. Although the Glock 22 is the standard sidearm of the FBI, this is a TV show and they focus on events and people rather than guns.
Heckler & Koch MK23
Used by a very pissed off Gorden whilst in a fire fight with Dean and Sam. Future Dean also uses one of these in the flash forward episode 'The End' which he carries in a thigh holster, which he uses to execute one of his ressistance fighters who has been infected with the croatoa virus - can someone upload a pic
Dean (Jensen Ackles) and Sam Winchester (Jared Padalecki) both use sawed-off shotguns loaded with rock salt throughout the series.
Remington 870
John gives Dean a Remington 870 shotgun in a flashback when he goes on a hunt.
Mossberg 935 Semiauto Shotgun
In what may be a continuity break, Dean is seen loading a short barreled Mossberg 935 before a fight in Season 3, Episode 1 "The Magnificent Seven". This was supposed to be the short barreled Ithaca 37 seen in other episodes of the show, but Dean was loading the gun without the barrel and the magazine tube was obviously not the Ithaca 37 by the Mossberg 935.
Winchester 1300
Used by police and the guy that shot himself (see gunstore).
Dean (Jensen Ackles) used this briefly. He was about to snipe a baddie, but was mind-controlled into trying to kill himself.
Unknown Sniper rifles
Used by Police Snipers to gun down Ron during the "bank robbery".
Remington 7600
A redneck used this rifle until Sam knocks him out, but he couldn't get it to work.
Unknown Rifles
There are seveal unknown rifles used throughout the series.
Heckler & Koch SL8
A Heckler & Koch SL8 is used in the show. It has been upgraded with the SL8 sniper kit (threaded barrel, low profile scope rail) to replicate the SL9 rifle sold in Europe.
Also used by one of Deans resistance fighter's in the episode 'The End' fitted with what looks like a silencer and a scope, yet again here's a link as i dont know how to upload pics http://www.imdb.com/media/rm3394865408/tt1488984
M16 with A2 style handgrips
Used by conspiracy theorist Ron, who takes over a bank in hopes of killing a Shapeshifter, which he thought was a terminator. When Ron is gunned down by snipers, Dean takes the weapon and carries it through the rest of the episode.
I believe he thought it was a mandroid
This is just his dads weapon stash from the truckzilla's trunk
-Close. The weapon loadout is slightly different, also Sam has changed the symbol at the top to a Crucifix, and removed the second Crucifix between the revolver and the pistol on the middle left side.