777 advice

[tacfoley]

Nossir - this propellant is totally unsuitable for the .577 anything - especially in such a fine grain size. The real thing used Fg.

Large calibre replica or genuine muzzleloaders shoots tend not to shoot a Minie bullet with much degree of success when trying to equal the original BP load. Big loads of 777 can blow the centre out of the bullet, leaving the skirt in the bore for you to find next time you load it up. Preventing the bullet from being seated on the charge can have catastrophic effects when next fired. A bulged barrel can be the very least of your worries.

The previous owner knew what he was doing, IMO, so my advice to you is to replicate HIS loads, not try and get centre-fire rifle performance out of a 170-year old design.

You may, of course, ignore this advice.

tac

Post amended in the light of other posts