12ga Blank Fired Slug

thingiverse

Ammo is expensive. So how about a 3D Printable Rifled Slug fired with 22 caliber blanks (ramset blanks) available at any hardware store. The lower portion that would typically be brass is meant to have the blank inserted, with it offset so a centerfire firing pin will ignite the primer in the rim. The cavity above the blank acts as an expansion chamber and causes the slug to separate at the perforated line. The lower portion can then be ejected with the spent casing inside. The slug itself is rifled to work with a smoothbore shotgun. This is a beta version at the moment so I'm only posting the .obj files. I have a few other versions in mind should this be successful for everyone. Some (charlie?) versions I'm working on: 1. Addition of a cavity that allows you to pause the print, drop in some washers or nuts for weight, then resume the print to encapsulate them. 2. Addition of a cavity to retain extra powder from a second (or more) blank. 3. Slugs with printable obturating bands for added gas seal around the slug. (Obturating bands work like the piston rings in your car's engine, or the gas rings on your AR bolt. ***It was designed for a pump action shotgun, and has not been tested in a semi-auto.*** As always, what you do with your stuff is your problem. Don't be an idiot. Print at 100% infill. The rim should come out at a diameter of 0.87 inches, the "brass" section should be 0.809 inches, and the slug should measure 0.729 inches. Your tolerances may vary, but it is for a shotgun. ***Update 3 Mar 2022*** I have added two new beta versions: "Solid" is unchanged. "Nut" is intended to pause the print at the last layer of the hexagonal cavity, drop in a standard 3/8x16 nut, then resume the print. This will add additional mass to the slug. "Ring" has the addition of obturating bands, to help seal it against the bore and retain more velocity, then separating at the muzzle. Print 3 rings at a total thickness of 0.8mm, then stack them in the groove at the top of the projectile. **IMPORTANT** the openings in each ring must be offset from each other around the slug. 120 degrees apart is optimal, but as long as they aren't lined up they should seal better; conforming to the bore. Again, this is all still a beta version at the moment. Happy printing. ***Update 9 Mar 2022*** Minor tweaks made based on feedback for cycling through a pump action magazine tube, and relief added around the blank rim for firing pin clearance. Recommend to print as all walls. If needed, ream the blank cavity with a 5.7mm drill bit. It should be a light press fit, or glued in. Do NOT put this in a firearm if the blank can fall out and get lodged in the operating group!! The rim can be crushed igniting the blank outside of the chamber. ***Update 10 Mar*** Included photos of fired/recovered slug. Reduced slug diameter based on feedback from beta testers to compensate for variations in bore diameters. ***Update 12 Mar*** Out of Beta and into the internet. The step file is included. Enjoy.