I wound up with a set of 5.7x28 dies in a convoluted trade. A little study convinced me that they shouldn't be used to reload the weapons that the cartridge was designed for, but a Handi in 22mag reamed out and a .223 extractor might be a different story.
A rimless 22 hornet for all intents and purposes, but different.
I would buy a reamer and donate it to the program, but there wouldn't be much point if nobody else would ever be interested.
If you want to try a single-shot application of a machine pistol cartridge, vote for it here. If no one does, I'll forget it.