Elwood (Ethan Suplee) wields a Mossberg 590 shotgun in the scene where the boys stumble upon he and Dennis' pot field, he fires several shots, missing the fleeing boys.
Elwood (Ethan Suplee) trades his Mossberg 590 shotgun for the more traditional Mossberg 500 shotgun (which is seen again later in full, showing it has an extended magazine tube). Sheriff Briggs (Ray Baker) is also seen using the Mossberg 500 later, showing off its extended magazine tube, when he meets up with Elwood and Dennis at the end of the film. At first glance it appeared to be a Winchester 1300 shotgun, but a closer look at the location of the safety shows it is a Mossberg 500.
Dennis (Abraham Benrubi) uses an L1A1 inch pattern rifle with a laser scope as his weapon of choice throughout the film. The rifle has a custom flash hider not usually attached to the L1A1. The inch pattern is evident by the front sight and the rear sight as well as details in the upper receiver and pattern of the foregrips.
Elwood later uses an M16A1 rifle, fitted with Cobray 37mm Flare Launcher. Towards the end of the film, Dan (Seth Green) picks up Elwood's M16A1 but shows his lack of experiance as it fires wildly ( if you look closely there is no bolt) .
I think he means when Seth Green is holding the gun, you can't see the bolt inside the ejection port. This is because the gun is empty, it does have a bolt. - Gunmaster45
Elwood uses a blued Beretta 92SB as his sidearm, as noted by the rounded trigger guard. The county police are seen with 92SBs in their holsters as well. (They are assumed 92SBs because why buy another gun if you don't even see it?)
Del Knox (Burt Reynolds) keeps two Colt Single Action Armies in cross draw holsters. He uses them to blow up Dennis and Elwood's ATV, stopping the assault. He fans them from both the left and right hands, holding 5 shots in each, A well know safety precaution with old six shots. Load 5 bullets and drop the hammer on an empty chamber. They are only briefly seen and could be Uberti, Cimmeron, or Ruger Vaquero copies, or perhaps genuine Colts.
An unknown grenade is used by Elwood, who drops it when Dan knocks him and Dennis into the mine shaft. Jerry (Matthew Lillard) picks it up and manages to luckily take out the three bad guys when the grenade blows up a tree, falling on them just in time. It is possibley a cigarette lighter.
