The SPECACT parts were added together with a DLC, the SPECACT Assault, Engineer, Medic and Recon individual DLC's, as well as a bundle DLC that included all four.
The SPECACT DLC for a particular class gave you an extra weapon, basically a "SPECACT" version of one of the better weapons for that class, unlocked and ready for you to play with. It also gave you a "Kit" which is basically a different Camo-suite for you to wear.
On the menu, after installing the DLC, you can select either "Assault" or "Assault+" class to select which kit to use. The weapon is available to both classes, but not all game modes.
For the four classes, the weapons are:
- Assault: M16 SA
- Engineer: UMP SA
- Medic: MG3 SA
- Recon: M95 SA
The excellency pins are awared for reaching a kill count of 8 in any round with the specact weapons.
The efficiency pins are awarded for reaching a kill streak of 5 in any game round with the specact weapons.
The Insignias are awarded for reaching a total kill count across game rounds of 100 with the specact kits.
On Xbox 360 and PS3, there are achievements and trophies that are awared for getting all 3 awards (excellency pin, efficiency pin and insignia) for a particular class. On Xbox 360 these are worth 15GP apiece.
Best Answer
You need to equip this part of your class's vehicle specialization:
Alternate Weapon Package
A weapons package that upgrades the targeting systems of vehicles and helicopters. It extends the effective range and accuracy of mounted weapons. - Adds an alternate weapons to the vehicle. Such as the M1A1, will have a secondary machine gun that you can control along with your main gun.
Its a vehicle specialization and requires 10,000 vehicle experience points to unlock.
More details here.