under barrel shotgun

handles for Pvc body 1in outer diameter ~18 in long secure a spring at one point of the tube and drill a hole where you want the pin to go in and how far the spring compresses

chose with or without grip
I suggest making extra pins and pre making weak point repairs

the weak point repairs are replacements for a part that commonly breaks the part that hooks on to the rail( 21mm) to attach the repair I use a wood burning tip with a large face

und_brl ram is meant to attach to an 7.5mm aluminum arrow body and is needed to push the spring down so the pull pin can be placed

I believe I used

https://www.homedepot.com/p/Hillman-1-4-in-x-3-in-Cotter-Less-Hitch-Pin-3-Pack-881124/204726207

For the pins