Heavy Gunner Abilities:
Squaddie:
Extra Mags: If you are missing ammo at the start of your turn your soldier will perform a quick reload to regain 1 ammo. This can occur 6 times a mission. Also gives the unit an ammo slot.
Supression: Same as the vanilla Skill.
Area Lockdown: Fire a barrage that pins down multiple targets within a 5-tile radius, granting reaction fire against anyone that moves or attacks. 3-Turn Cooldown. Can be a AWC perk.

Bulldozer tree
Corporal: Combat Fitness: Gain a +1 HP, +1 mobility, and +5 dodge. Can be a AWC perk.
Sergeant: Shredder: Same as the vanilla Skill.
lieutenant: Chain Shot: Same as the vanilla Skill.
Captain: Bracing Stance: The soldier can brace themselves causing them to gain extra aim, and allow their reaction fire to critically hit. While this ability is active the soldier has a penalty to mobility.
Major: Traverse Fire: Taking a standard shot with your primary weapon as your first action no longer ends your turn.
Colonel: Cyclic Fire: Special Shot: Fire three shots at a target. All shots have aim penalties and increased crit chance. 6-turn cooldown.

Fire Support tree
Corporal: Grazing Fire: Missed shots with your primary weapon have an additional roll to become a graze.
Sergeant: Lock on: Your supression shots, Area lockdown shots and Primary weapon overwatch shots gain a +15 bonus to hit.
lieutenant: Juggernaut: The soldier equips Special gear. The gear reduces the chance of being crit by 25%, and allows them to occasionally Armor up giving them temporary bonus armor at a small cost to mobility.
Captain: Mayhem: All suppression and area lockdown shots deal 40% more damage.
Major: Area Barrage: Open fire on all targets in an area. Targets damaged by this barrage have their mobility reduced by 5 for 2 turns.
Colonel: Rupture: Same as the vanilla Skill.

Personal Defense tree
Corporal: Duelist: All your Pistol shots deal increased damage, pierce armor, and have increased chance to hit.
Sergeant: Quickdraw: Same as the vanilla Skill.
lieutenant: Crippling Fire: Shot deals less damage but disorients a target for 3 turns and shot has high crit chance. 3 Turn Cooldown. Can be a AWC perk.
Captain: Defensive Watch: Gain +1 Overwatch shot and +1 armor per action point remaining when you activate Overwatch.
Major: Sidearm Expert: You gain the return fire and lightning hands perks.
Colonel: Fanfire: Same as the vanilla Skill.