Airsoft PPS double barrel shotgun (STL ONLY)

This is a simple Airsoft double barrel shotgun design that uses a double stage trigger, meaning you can fire the shells separately with half trigger pulls, or both at once if you give it a full trigger pull. Breaking it open extends the extractor which makes replacing fired shells easier.

You can choose a long or short barrel. There is also a stock option in addition to the stockless version pictured. The gun in the picture uses a short barrel.

Hardware:

• A bunch of M2.5 x 10 mm screws, preferably self tapping and countersunk. You'll need about 20.
• Some 4 mm diameter compression springs with about 0.4 mm wire diameter for the trigger and break lock. You might be able to salvage these from pens.
• M5 x 30 mm bolt with a respective M5 nut for the hinge. The bolt should be countersunk.
• A 4 mm diameter 0.4 mm wire thickness extension spring for the extractor.
• Two 3 mm pin diameter pins, one 30mm long and the other 20 mm long. You can usually find brass ones at your local hobby store and cut them to length with a dremel or a metal hacksaw.
• You will need two Airsoft spec barrels. You can use the pricier precision ones or just salvage some stock ones that you don't need if you don't mind somewhat higher spread. Cut off the bit with the hole for a hop up since it will only interfere with BB travel. If you are going for a short design, you'll need two 130 mm inner barrels and if you want the long one, use 265 mm.
• Most importantly, PPS gas shells. I haven't tested the design with 6 BB metal shells made by other manufacturers so I can' guarantee those would work but if you want to be sure pick up the version of this design with .STEP files and adjust the tolerances and/or modify the sealing ring.
• Some CA glue. Activator makes assembly easier as well.

Printing notes:

• .15 Layer height
• Tree supports recommended, will save you lots of headache.
• Cura slicer recommended
• You will have to orient the pieces yourself. The correct orientation shown in picture provided.
• Small printer should be enough - 20x20cm bed works.
• Trigger doesn't have much of a contact area with the bed so you might want to use a raft for that.
• For a stockless design, print the Grip. For a design with a stock, print Stock A, B, C and insert A, B.
• For a long barrel, print BarrelB2. For a short barrel, print BarrelB.