FN Herstal SLP Mark I 12 Gauge Semi-Auto Shotgun, 22 in Barrel, Invector Chokes, Active Valve Gas, 8+1
This FN Herstal SLP Mark I is a 12 gauge, gas-operated semi-automatic with a 22 in barrel, built around FN's Active Valve short-stroke system and chambered for both 2 3/4 in and 3 in shells. It features a barrel-mounted cantilever rail, along with a fiber-optic front sight and a folding rear sight, an 8+1 capacity (2 3/4 in), and thoughtful custom additions including a receiver-mounted shell carrier and an extended Picatinny rail under the forend. Belgian manufacture and clear factory rollmarks add to its appeal for shooters and FN enthusiasts alike.
Condition
Overall Condition: Good condition, showing some signs of prior use and handling.
Bore Condition: Good - Clean, well-maintained, minor wear marks.
Specific Condition Notes: There are visible scratches and small blemishes on the exterior, including noticeable finish scratches on the barrel.
What’s Included
- FN Herstal factory hard case
- FN owner's manual
- Standard Invector Modified choke tube (flush)
- Extended ported choke tube
- Invector choke wrench
- FN SLP gas piston
- OEM trigger pins
- FN factory magazine tube extension (installed)
- Receiver-mounted shell carrier (installed)
- Extended Picatinny rail under forend (installed)
The SLP Mark I pairs a 22 in choke-threaded barrel and Standard Invector choke system with FN's Active Valve short-stroke gas operation. It is built to run 2 3/4 in and 3 in shells and is configured with an 8+1 capacity (2 3/4 in). The alloy receiver wears a matte black finish, matched to a black synthetic stock and fore-end with molded checkering and a ventilated recoil pad. Length of pull is 14.0 in.
Target acquisition is supported by a red fiber-optic front sight and a low-profile, fold-down adjustable rear blade, with a barrel cantilever rail that bridges over the receiver. The gun also includes a receiver-mounted shell carrier (side-saddle), plus an extended accessory Picatinny rail under the magazine area for mounting gear as desired.
This SLP Mark I uses the Standard Invector choke interface. An improved cylinder choke is installed. A modified choke is included, along with an extended ported choke tube, giving you practical options for different loads and distances.
Controls are straightforward: a right-side charging handle, a bolt release located ahead of the trigger guard, and a cross-bolt safety with a red indicator ring. Factory markings are present, including the FN oval logo and rollmarks such as "FN HERSTAL BELGIUM," "FNH USA FREDERICKSBURG, VA," "FN 12 GA – 2 3/4, 3" INVECTOR SLP MK1," and "3" MAGNUM."