I have two Petersolis that I have a love/hate relationship with. They both work well, when they work properly, but the locks on both are slow and very sloppy.
I am currently re-building the lock on the bess. The hole in the bridle was .033 larger than the axle on the tumbler, AND was drilled about 8 degrees off perpendicular to the face of the bridle. The hole in the lockplate is .015 larger than the axle. Both faces of the tumbler are filed convex to compensate for the sloppy fit of tumbler to bridle, which causes the mainspring to bear on, and wear a grove in the bridle. The top of the tumbler has also worn a grove in the bridle.
The bridle, BTW, was not hardened, and the hardening on the tumbler appears to inconsistent as well. The axle on the bridle side of the tumbler appears to be hardened, but the axle on the plate side does not appear to be hardened.
Both axels were left as cast, as opposed to being machined smooth and concentric.
Petersoli's Bess frizzens are notorious for thin case hardening so I plan to half-sole the frizzen to make it right.
Petersoli's springs aren't all that great either. New, high quality springs should make a marked improvement in faster, more reliable ingition.
The toe of the frizzen on the .32 is too far back to trip over at the right time, and the back of the toe was milled down so only about half of the thicnkness of the toe exists, so there is little material work with to fix that problem.
The powder chamber in the breech of the .32 was only .240. Less than 1/4 of an inch in diameter. The powder chamber was enlarged to .300, and the length of the touch hole liner reduced to equal the thickness of the barrel/breech assembly. The liner was coned a bit on both the inside and out to improve ignition, and it still ain't right.
A better solution might have been to form a funnel at the mouth of the powder cavity to help funnel powder into the breech.
Though the lock on the rifle appears to be of better fit and finish than the bess, the bulk of the problem, IMHO, appears to be in the poor design of the lock, and with the way the rifle barrel is attached to the stock. The barrel is fastened to the stock with screws running through the thimbles and into tennons dovetailed into the bottom of the barrel. IMHO, This is a serious design flaw that is difficult to fix properly, in a home work shop.
With my experience, and the experience of others who have similar problems with Petersoli locks, IMHO, I would look at higher quality guns, as opposed to trying to deal with the sloppy locks and thin case hardening on Petersoli's flint guns.
J.D.