12 GAUGE FLARE PISTOL
flare pistol parts MeshLab
* UNTESTED EXPERIMENTAL DESIGN *
* NEVER TRY TO FIRE AN ACTUAL 12 GAUGE SHOTSHELL – IT ~WILL~ EXPLODE IN YOUR HAND! *
This pistol was designed entirely in Google SketchUp and is chambered to fire a 12 gauge signal flare. It is unknown whether it can handle the pressure of even these low-pressure rounds, but this will soon be discovered through experimentation.
It is a simple break-barrel design. It fires from the open bolt. The bolt doubles as the striker/firing pin. Elastic bands on both sides of the pistol serve as the striker spring, and this is also what holds the breech closed. There is no trigger return spring, but a rubber band could easily serve this purpose if desired. Manually holding the trigger forward during cocking should be sufficient, as the pressure of the bolt resting on the sear should create enough friction to hold it in the cocked position.
At the moment, there is no mechanism to affix the grip to the frame. Glue or epoxy would probably work. Subsequent designs will have a pinned dovetail or some other means to attach the grip without glue.
With a subcaliber adapter, this flare pistol could probably be converted to fire a low pressure .22 round (CB or Super Colibri come to mind). Be advised that doing this could put you in violation of the NFA, as it could then be termed an “Undetectable Firearm” or an AOW/Unconventional Pistol. To avoid this designation, one could use a rifled subcaliber adapter and glue aluminum foil to the exterior of the pistol. In my mind, taking these measures would render such a pistol perfectly legal, but then I am no attorney. If built as designed (to fire signal flares only), it should be exempt from these provisions. Even the common Orion flare pistol sold at boating supply stores is of polymer construction and features a smooth bore. Therefore I do not believe flare pistols are subject to these regulations.
* PRINT AT YOUR OWN RISK! *
* ASSEMBLE AT YOUR OWN RISK! *
* FIRE AT YOUR OWN RISK! *
The author of these files assumes no responsibility for the actions of anyone. Any sane person would assume appropriate precautions when test firing such a device (e.g. mounting it in a vise behind sandbags and pulling the trigger with a long piece of string). If someone else tests it with ABS and says it’s fine, don’t print it in PLA and assume the same (or vice versa). There is nothing safe about this design, and even a minor variation in materials or printing method could cause a catastrophic failure.
I designed the barrel to be as strong as possible. It’s 1.6″ wide (twice the diameter of a 12 gauge flare round), so there’s a thick ring of .4″ polymer surrounding the chamber on all sides. The barrel could be shortened if desired, but I would advise against making the chamber wall any thinner.
Areas with interlocking parts (e.g. the bolt/receiver interface and the trigger/sear) have been designed with slight gaps such that they will hopefully drop into place with little or no manual fitting. These dimensions may be altered once sufficient data is gathered from prototyping cycles.
Mad props to the first person who successfully prints and assembles this thing. All design files are hereby released into the Public Domain. Have fun.