Nerf vertical shotgun pump grip

This is a very short pump grip with some picatiny rail on the bottom. This file is meant to be used with my Retaliator and Magnus shotgun parts:
https://www.thingiverse.com/thing:3053220
https://www.thingiverse.com/thing:2590061

I designed this part to make one of my 3D printed shotgun-i-fied Retaliators as short as possible. I also made a few vertical grips to go along with this file:
https://www.thingiverse.com/thing:3374945

The pump grip has pockets for M4 nuts. You'll need to find the appropriate length of M4 bolt for the thickness of your priming bar material.