When I came back to BP shooting and hunting after a long layoff I didn't have much in the way of shop space or tools, so bought a lefty GP of the flint persuasion in 54 caliber. Glad I did! Rifle has been very reliable and accurate. This was purchased in 2005, so is of Investarms manufacture.
I can't resist tinkering with things, so did make a few changes, mostly of a cosmetic nature. Coned the outside of the vent insert to give the flash slightly better access. Lightly sanded the stock, then applied several coats of True Oil to finish filling the grain, then dulled it down with four ought steel wool. Refinished all the metal brown with Birchwood Casey Plum Brown, heating the metal with a Harbor Freight heat gun- looks very nice, changes the character of the gun.
Found the lock works best with 5/8ths inch flints. Gunk can build up in the recess in the breech plug, so I clean that with a 38/357 pistol bore brush. Velocity is more consistent with a pan nearly full of powder.