Wait until you shoot the lock. If your caps freeze to the nipple so that you have to use needle nose plyers to get them off, consider grinding or filing a notch in the front of the skirt on the hammer. If the skirt is wide enough, the caps should break freen and come off whether there is a notch in the hammer skirt or not. More important, you need to check your final alignment of the hammer to the top of the nipple to see if the hammer is hitting it squarely. Put some lipstick or stock inletting marker on the top of the nipple and lower the hammer down on the nipple. Cock the hammer back, and tilt the gun up so you can look inside the skirt to see what kind of mark has been left. If you have a complete ring, everything is fine. If not, the marking dye will be on the high side. You can bend the hammer, which is difficult to do and get it exactly correct, or, easier, use a dremel type tool with a small grinding bit to grind off the high spot on the face of the hammer. It is a trial and grind process until you get a full ring. My final check involves taking a paper napkin, or paper towel, folding it a couple of times, holding it over the nipple and tripping the hammer. You should see a hole punched into the paper as if you were using a paper punch. If the hole is cut all the way around, you are done, If not, you have a little more grinding to do. Easy.
You do want the nipple to be struck by the center of the hammer, so that no side of the skirt is rubbing against the nipple or the cap. That can cause a misfire. So, do check the alignment. I had a drum and nipple arangement on my first percussion gun that was so badly out of alignment, that a gunsmith had to chuck the drum in a lathe, and take another turn off the inside of the drum to make it fit properly. Then we had to file down the threaded portion that screwed into the barrel, as it was now too long, and prevented my cleaning jag from getting down into the chamber. Once we had the drum aligned, we then had to bend the hammer a little to get the hammer centered over the nipple. Then I had to grind down the surface of the hammer so it struck the nipple square. A lot of work that should have done at the factory.
