Given the military realities of the galaxy, often small units of highly trained individuals can have a greater impact than massed troops. In order to ensure that they always have those sorts of individuals available, modern militaries select particularly talented soldiers to undergo additional training.

Heavy Gunner: When using an autofire-only weapon, you may brace it using only one Swift action. Additionally, you may use your Strength modifier instead of your Dexterity modifier when making ranged attacks with weapons in the Heavy Weapons proficiency group.
Prerequisites: Weapon Proficiency (Heavy Weapons)

Grenadier: You may reroll any attack roll you make with a grenade, whether thrown or propelled by a grenade launcher. The range increments for all of your attacks with grenades also extend by two squares.

Improved Heavy Gunner: Whenever you take the Full Attack action with an autofire-only weapon, that weapon is considered braced until the end of your turn.
Prerequisites: Heavy Gunner

Close Combat: Enemies you threaten provoke Attacks of Opportunity from you when making ranged attacks.
Prerequisites: Martial Arts I

Improved Autofire: When making autofire attacks, you may choose an area that is 1 square by 4 squares. Alternatively, you may choose to target an area that is 3 squares by 3 squares.
Prerequisites: Weapon Proficiency (Heavy Weapons)

Vanguard: Whenever an opponent makes a ranged attack against you in the Surprise Round, you may make an immediate attack against them as a reaction. This ability triggers only once per round, and only if you are not flat footed.
Prerequisites: Point Blank Shot, Skill Focus (Initiative)