In Season 3's "The Leap Home, Part 2" (S3E02), Sam Beckett (Scott Bakula) carries a Stoner 63 configured to be belt-fed as part of his brother Tom's unit in Vietnam.
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". Sam is seen getting it ready during a possible ambush.
In Season 5's "Lee Harvey Oswald", Sam is seen "leaping" into the body of Lee Harvey Oswald and holds the Carcano M91/38, the infamous rifle of the JFK assassination.