That's the one Tac - the originals were rifled I believe.

What is 'tow' as in ' a ball of tow'?

Enfield - thanks for that. The balls I'm using have to be pushed down the barrel with the ram rod so would almost certainly stay in place with out the top wad - I'll try it.

I've been using quite a bit of priming powder too, will reduce that and try again. Thanks Gents!