Rock lock.
Flinters can be finicky.
I have both, love my rock locks.
This one is mine.
MINE! ALL MINE!!!!
http://www.custommuzzleloaders.com/buckscounty.html
AAAA fancy maple, Colrain swamped barrel, caliber .40.
A round ball shooter.
I've shot it with as little as 10 grains of Swiss 3 f g .
Like a .22 rimfire but slower to reload.
Much slower.
The builder is a master.
I also have a .45 round ball shooter rock lock but the
maker is unknown.
A plain looking rifle but hey! It's a muzzle loader and it's
FUN and accurate.
It isn't "period correct" as it was built by an apprentice but
has nice wood, not fancy, but nice.
I didn't pay too much either.
The fancy one cost me a grand back then.
Today??? $5,000 wouldn't touch one IF you could fine
one that nice.
Go here if you want to slobber and drool.
https://www.trackofthewolf.com/
Oh! I also have a lifetime supply of Goex (yuk),
Schuetzen (sp?) and SWISS.
Lots of Swiss, 3 and 4 f g.
Swiss is about the best there is on today's market.
Check powderinc.com