Nitro
As far as using spent cases as snap caps.......
If you are talking doubles, DON'T DO IT unless you fit new unfired primers each time you pull a trigger!!!
In my opinion there are PROPER snap caps and there are RUBBISH snap caps.
Yes PROPER snap caps are not cheap but this is because they are not cheap to make.
Cheap snap caps can break your lock parts which are not so cheap to replace!
I make snap caps for any cal in both brass and aluminium and if you need a set maybe we can do a deal.
These are fitted with adjustable spring loaded polycabonate plungers.
I think that Taylor said something in one of his books about snapping away to your hearts content with a double using snap caps but I think you'd have to be CRAZY to do so.