It sounds like you were unlucky enough to get a bad repro. From the ones I have shot and used I have had no problems at all. From owners I have heard very few bad things too. I would take a Pedersoli over those cheap made in India repro's.I bought one. Worse bore stuffer I ever owned. I was glad when the ole lady won it in the devorce.
I had an 1803 Harpers Ferry. First off, it wasnt an 1803. It was an 1803-14 a combo of designs over a few years. The trigger gaurd broke off, and I replaced it with a Rifle shoppe casted from an original. One heck of a fitting process.
The lock was pure garbage. The Frizzen spring was set to 300lbs, 7-10 is the norm. It sent the frizzen down range on the 8th shot. We ended up making a new one, seem they didnt have any spare for warranty parts.
I do not miss my fine blonde EX, or the rifle she took with her. Misery deserved company