Blaster (Patrick Warburton) carries an AR-15/SP1 fitted with the M203 grenade launcher in Season 3's "The Leap Home, Part 2" (S3E02).
Error creating thumbnail: File missingScreen used Faux M203 39mm launcher attached to an M16/SP1 rifle. Note that the film used multiple rifle/launcher combos, and the wear on the launcher actually changes from shot to shot, indicating that the actor is using the backup rifle/launcher combo for that particular shot.Error creating thumbnail: File missingBlaster (Patrick Warburton) carries an AR-15/SP1 fitted with the M203 grenade launcher in Season 3's "The Leap Home, Part 2" (S3E02).
CAR-15
Several members of the squad including Tom Beckett carry the CAR-15 in Season 3's "The Leap Home, Part 2" (S3E02). The episode takes place in April of 1970, so the curved 30-round magazines would not be anachronistic.
Error creating thumbnail: File missingCommercial CAR-15 Rifle with a fake XM177 flash hider welded on to make the barrel a legal 16" for commercial sale - 5.56mmError creating thumbnail: File missingSeveral members of the squad including Tom Beckett carry the CAR-15 in Season 3's "The Leap Home, Part 2" (S3E02).
M134 Minigun
An M134 Minigun is seen mounted in a bunker at the squad's Area of Operations in Season 3's "The Leap Home, Part 2" (S3E02).
In Season 5's "Lee Harvey Oswald, Part 2" (S5E02), Sam is seen "leaping" into the body of Lee Harvey Oswald and holds the Carcano M91/38, the infamous rifle of the JFK assassination.
In Season 5's "Lee Harvey Oswald, Part 1" (S5E01), the M1 Garand is used by Sam when he leaps into the body of Lee Harvey Oswald during Marine training.
In what appears to be a Ruger Mini 14 GB with Folding Stock, a State Trooper arrests Sam Beckett in S5E17 " Revenge of the Evil Leaper - September 16, 1987"
Error creating thumbnail: File missingState trooper to the left holds a Ruger Mini 14 gb with folding stock in S5E17 " Revenge of the Evil Leaper - September 16, 1987" - .5.56mm