Sharps percussioncarbine

[Old Scout]

Does anyone have experience with the Sharps percussion carbines or rifles? I have an original carbine that does not have the breach seal device, which I have shot with no difficulty. I recently got a Pedersoli Sharps carbine ( '63) with the moving breach seal. I can't get more than 5 rds through this gun till the fowling between the breach block and seal plate locks it up!.
I've tried several types of grease, which got me from 3 rds to 5 rds! Any ideas?

Old Scout