Hello:
I don't know of any commercial ones. Mine are home made using regular brass with a HARD nylon insert in place of a primer. They hold up well enough and when the hard nylon looks weakened, I replace it. I suppose you could also use ONCE fired empties for only one more impact on the primer. High grade commercial snap caps usually have a spring backed brass impact area in place of a primer. These could be custom made, but they might be very expensive.
Regards, Kevin/El Supremo