Yes, flinter or caplock, on a caplock just remove the nipple and sift a little priming powder into the flash channel and reinstall the nipple, make sure the powder is as far in the flash channel as you can get it and it doesn't keep the nipple from being fully tightened. If the ball doesn't discharge because there wasn't enough powder, reseat the ball with the ramrod before trying it again. It doesn't take much powder to get the ball out, just a few grains. This works on a wet load sometimes too, just depends on how wet or contaminated the main charge is.
Tim