Elephant is a 2003 film directed by Gus Van Sant (Milk) that depicts a day in the life of high school students, two of whom later go on a shooting rampage. The film is based in part on the tragic events surrounding the 1999 Columbine shooting.
The following weapons were used in the film Elephant:
Eric (Eric Deulen) is seen carrying a Intratec TEC-9 semi-automatic pistol. Alex refers to it by name as a "TEC-9".
Unknown Pistol
While planning the attack, Alex and Eric mention their arsenal of weapons. Alex mentions that they have pistols. One of these pistols is seen on Eric's right hip. It is never taken out of the holster, used, or even seen closely enough to identify, but it looks like it is possibly a SIG-Sauer pistol.
An Internet gun sales site appears to offer for sale a nickel Ortgies Pocket Pistol with wood grips.
Rifles
Bushmaster Carbon 15 R21
Throughout the film, Alex carries a Bushmaster Carbon 15 R21 semi-automatic carbine. For the rifle, he modifies and tapes two thirty-round magazines together "jungle style". Alex refers to the rifle as a ".223".
Shotguns
Mossberg 590 Compact Cruiser
An Internet gun sales site appears to offer for sale a shotgun that resembles a Mariner variant of the Mossberg 590 Compact Cruiser. The shotgun seen on the site appears to be Photoshopped from several different weapons (most likely to avoid copyright infringement).
Mossberg 500 Cruiser
Throughout the film, Alex (Alex Frost) carries a Mossberg 500 Cruiser. He refers to it as "the shotty" and keeps it on his back, although he occasionally carries it instead of his rifle.