New South Wales Police 3d guns
Courtesy NSW Police Force

Australians making 3D printed guns have came up with an interesting way to get around the durability problem: interchangeable disposable barrels.

The frame appears to be based on the Songbird design that’s floating around the internet. Originally chambered in .22 with a plastic barrel and break-open action, the design was eventually upgraded to use a barrel liner and fire .357 Magnum rounds. The design definitely wasn’t great compared to commercially-built guns, but it worked and left the user with all their digits.

Instead of operating as a break-open action, this variant has a thicker barrel built into a removable piece. The rear appears to be made to accept rimmed cartridges like the .357 Magnum or .38 Special, as you can see a recessed space at the back of the chamber for a rim.

This allows the cartridge to headspace on the rim, but be flush with the back of the barrel so the action can still close up.

The disposable barrels’ chambers. Note the space for a rim behind the chamber.

When the NSW Police Force seized the guns, there were multiple barrels per gun, implying that the barrel was designed to be disposable and/or quickly replaced with another. This may be due to limited durability of the barrel itself (only firing one or two shots). Or it may be that the sleeve that holds the barrel may melt with too much use in a short period.

By switching out the barrel and let it cool, the assembly’s duty cycle is reduced by 50%, allowing for more durability. If one or two shots is all it takes to melt down, then replacing the whole barrel assembly makes a lot of sense.

Like any older Songbird, the frame has a trigger assembly that drives a firing pin into the primer. We don’t see a place for a rubber band, so it likely has a spring inside to accomplish all this like other newer Songbird designs.

Ways This Could Be Improved

If one were unable to get cases for ammunition somehow, this design could be modified to allow for muzzle loading. If one could get a pipe for the barrel that was closed up at one end, a primer pocket could be drilled directly into the rear of the chamber, followed by a flash hole.

Powder could then be poured into the muzzle and a cast bullet pushed back until seated on the powder. This would allow for a way to keep spare ammunition in a pocket or pouch, replacing the whole loaded barrel for follow-up shots, and possibly retained for subsequent reloading later.

Powder and even primers could be made without regulated parts, using procedures outlined in this old Army field manual.

Whether cartridge-fed or muzzle loaded, this design could be turned into a revolver. Instead of replacing a whole barrel, the disposable/replaceable part could include just a chamber and forcing cone, and include 5 or 6 of them. Cylinders could be swapped in for more shots, like a speed loader. It would need to be mounted to the frame in such a way that the barrel doesn’t melt the frame down, but that would allow for a more usable firearm.

If only a forcing cone were included with the chamber, the package would be much smaller, probably not much bigger than a regular cartridge. It would probably be possible to load these forcing cone/chambers into a magazine, and then line them up with the back of a barrel similarly to a revolver. If these assemblies were muzzle loaded, bolt-action or possibly semi-auto firearms would be possible without cartridges. This would be definitely be chunky and ugly, but would at least work.

Obviously modern cartridges are preferable to any of this, but if you’re desperate enough to be relying on a Songbird-derived design for armed defense, you’ll do what you can. Either way, it’s clear that, increasingly, gun banners can’t stop the signal.

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