Spread: (show with 1*1*1 missile top, wide secton facing outwards on the front) Affects everything within a 15º cone side.
Plasma: +3 damage
Auger: goes through In-organic matter (apply apropiate penalties)
Napalm: +2 damage, do 1d6 damage to everything within 2"
Pistol: (mount a megaphone to the underside) +2 damage, can be used as pistol if main weapon malfunctions.
Shotgun: (mount a BA shotgun with a BA monopod to the underside) +4 damage can be used as a rifle.......... etc
Plasma: +3 damage.
Auger: goes through In-organic matter (apply apropiate penalties).
Uranium: +2 damage, if it hits a livin creature it has 1d4+2 radiation damage everyone of his action phases until it dies or is steralised.
(Same as rifle +)
50cal: +5 damage +2" range.
you can have only one upgrade per section I,E, one barrel upgrade, but multiple upgrades on a weapon. feel free to post more ideas so i can improve.