These are printable base wads for pistol cartridge shotshells such as those using these shot caps:

I tried these as an experiment to avoid the tedium of punching and setting heavy cardstock wads. They actually seem to work just fine, and are much easier to load using the included wadsetter.

The concave base is not necessarily an attempt at forming a gas cup. It's more of a way to conserve case volume while allowing for adequate bore contact length for wad stability. For the same wad height, these wads allow a slightly larger powder charge when compared to a card stack.

For my application, I preferred the extra-tight fit of an oversize TPU wad. Much like having adequate neck tension, a tight wad ensures adequate early pressures and can help ensure consistent burn performance with slower powders. This is important, as the shot cap can't provide any significant tension itself.

I've used both PLA and 98A (JAYO silk) TPU without any issues with wads bursting or smearing (3 walls, 7 top/bottom). All the recovered wads had clearly engraved rifling, showing full bore contact. I have not noticed any powder degradation where in contact with the wad. That said, I'm using less-plasticized materials and a slower powder (old Alcan AL-7). I can't say that's the case with softer TPU or faster double-base powders. I have not tried these with resin, but my other experiments with resin sabots suggest it wouldn't be tough enough. I also have more significant doubts about the resin being powder safe.

I'm also including a simple press-mounted wad setter. It should be configurable to work for other pistol cartridge shotshells or brass 410 hulls. The SCAD file is currently configured for 44 SPL/MAG shot shells, and a prerendered STL is included. See the SCAD file for design and printing notes.

The lock rings I used are here:

With my printer tolerances, I used the +1.0% variant of the pinch style nut.

Printables Tags: reloadingtools; firearms; shotshell; reloading