MK3A1

The Pancor MK3A1 or "The Jackhammer" is a 12-gauge, gas-operated, fully automatic shotgun. It was developed by John Anderson in 1984 and patented in 1987. Its cumbersome design and inability to cycle after 3 shells never led it to be fully produced; there are few (according to some reports, only two) prototypes in existence.

Battlefield 2
In Battlefield 2, the MK3A1 is the Tier one unlock for the Engineer Kit. Its main advantage is its fully-automatic firing mode, being only matched in fire rate by the MEC S12K. The shotgun is a valid replacement for the American M11-87 and Chinese NOR982 Pump-Action shotguns, as the MK3A1 has more power per shot, as well as boasting fully automatic fire.

Battlefield Play4Free
The MK3A1 is a shotgun set to appear in Battlefield Play4Free in a later patch. It holds ten 12-gauge shells and is fully-automatic.

Battlefield 3
"Fully automatic shotgun prototype developed in the US."

- Battlelog description The MK3A1 is in the Back to Karkand expansion along with 9 other weapons. It has more ammunition than the USAS-12 when equipped with extended magazines with 12+1 rounds available. It has high recoil if fired fully auto while aimed down the sight, but only after the first 3-4 shots. The ammo specialization is highly recommended, as the MK3A1 uses ammo very quickly. Equipping it on the Support class is another viable option, as the resupply seems faster with the MK3A1 equipped than with other weapons.

It is obtained after finishing the Scarred Veteran assignment, which involves having 10 kills with the PP-19, 5 kills with the DPV, 10 kills with the BTR-90, and playing 2 hours on both Gulf of Oman and Sharqi Peninsula. The assignment Familiar Territory must be completed prior to unlocking this assignment. Note that on consoles, the BTR only spawns at RU home and D flag on Oman, but can spawn in several locations on Oman, Sharqi, and even Strike at Karkand on PC. For these reasons, it is one of the hardest weapons to unlock in the Back to Karkand expansion.

Trivia

 * In Battlefield 3, upon unlocking extended magazines, an extended tubular magazine is displayed onscreen. This is odd, considering that the MK3A1 has a cylindrical magazine.
 * The MK3A1 feeds from a revolver style drum cylinder, so it does not chamber a round to gain a +1 as portrayed in Battlefield 3.
 * The MK3A1 is the only shotgun in Battlefield 3 that does not change visually when equipped with a flash suppressor.
 * The ACOG when equipped on this weapon shows the PK-A's reticule but, retains the zoom.
 * Before the March 2012 patch, the MK3A1 had a strange clicking in the reload sound that would have been played when the player attempted to insert a fresh magazine.
 * It shared the same firing sound as the USAS-12 and had Rifle Crosshairs prior to the March 2012 patch.
 * The suppressor, when equiped, failed to affect the weapon at all.
 * After the March patch, when firing full auto, the recoil animation disappears, showing the muzzle climb without any shaking. this can be countered by quickly tapping the fire button.
 * After the June 2012 patch, the ammunition capacity was increased to 8+1.
 * Even if the MK3A1 doesn't eject empty shells like a revolver, a sound of one or more shells bouncing on the ground can be heard.