It would be interesting to know what's actually in the commerical loads

The 9mm nitros I had were very quiet and couldn't burst a balloon, but were good for a quieter training round and when we once had to do a competition inside (I decided better to keep horse happy than to burst the balloons)

The nitro that blew up a trinity was a long cased home load I believe, so no crimp open ended. Hence my reluctance to mess with nitro.

Are dainty muzzle loaders common?

Also random question, but how much would you expect a dealer to charge to receive a firearm on your behalf? Quite a few have quoted £30