I recently bought at auction, sight unseen, a Stevens Tip-Up Single Shot Target Pistol. The hammer would not lock into cocked position when I first picked up the gun, but after playing with it it a bit, it began to catch and hold.
It had, however, an extremely light, hair-trigger trigger pull, and I was looking to try to adjust it. I removed the grips and found no adjustment. I fiddled with the screw by the trigger, and No, that did nothing. So, I decided to look inside. I assumed that if I removed the four screws, I could lift off the side-plate and get at the gun's internal works.
I was mistaken. There was no sideplate. It has a solid frame. The two rear screws actually simply held in place the trigger and the hammer. Once I unscrewed the bottom one, the trigger simply fell out. I see nothing to adjust.
Then, of course, I tried putting them back. Easier said than done. I think that cannot be done without first removing a spring. Basically, I need a gunsmith. Embarrassing, but true.