The Remington Model 7188 is a prototype automatic shotgun.
The 7188 was specifically developed for US Navy SEALs for use in the Vietnam War. It was well liked by the SEALs because of its sheer destructive power, but was said to recoil extremely hard. After the war, most 7188s were converted to semi-automatic operation and designated the Model 7180, despite retaining the weird selector switch.
The 7188 was basically a fully-automatic Remington Model 1100.
The 7188 used a bunch of custom loads, such as the nine-round XM162, the 27-round XM257, standard 12-gauge buckshot and a few custom 12-gauge silenced rounds.
The 7188 had many variants, in fact, six.
- Mk 1
It had an extended magazine, perforated barrel shroud, bayonet mount and adjustable rifle sights. This is the most common version.
- Mk 2
This was identical to the Mk 1, but had a ventilated barrel rib and front bead sights of a standard shotgun.
- Mk 3
It was identical to the Mk 1, but lacked the perforated barrel shroud.
- Mk 4
This was a Mk 3 with standard shotgun sights.
- Mk 5
This was a Mk 1 with no perforated barrel ribs and lacked an extended magazine.
- Mk 6
This was a Mk 5 with standard shotgun sights.