Trying them out in my Traditions St Louis Hawken .50cal 1:48 twist with 70gr Pyrodex P, .490" chilled lead round balls and .020" patch.

Awesome accuracy so far, but now I see the accuracy starting to drop off big time.

I figured since they were accuracy and easy to load like a soft lead ball, they would be great for rendezvous. Not the case as I have to have solid accuracy no matter how many shots I take.

Letting the rifle cool down for a bit before trying some more shots.

I'll have some pictures when I get back inside.

Cool down did not help! They simply just allow me 5 amazing shots and then they scatter all to hell.

You might try changing the nipple. Most times when one of my percussion guns goes from good accuracy to less than good with the same load, it's because the nipple flash hole has opened up. It happens pretty fast if you've been shooting conicals from the gun.

Or, perhaps you're losing concentration after five shots.

Not the nipple. After that I cleaned the bore and then went to off hand shooting to practice for rendezvous. Perfect after that.

That's strange. I've read that conicals that are harder tend to lead the barrel more then pure lead ones. But shooting a PRB that shouldn't be the issue. Could be just fouling in the bore.

Problem; Gun. Yours is different than anyone else's. You may need to clean the barrel every so many shots; every shot etc. What will work for others, may not work for you. You might want to kiss it when it shoots well, pat the barrel and say it's alright! when YOU miss. Find out what works for you and your gun, (and in your mind. That all takes time and adjusting. Good luck and have fun.

If you were shooting your shots in rapid order the barrel would have heated up and expanded such that there may be a spot in the barrel channel that is applying a different pressure to the barrel when it heats up , thus changing the POI. Take your time between shots. If you start to notice that it is harder to load the next ball, you may need to swab the bore after so many shot to maintain accuracy. Several of my guns require that I swab the bore after 2-3 shots. If I don't, they are much harder to load, and the POI is different from the first 2-3 shots.

Jon I'd be interested to see what kind of groups you would get swabbing after every or every other shot. Keep us posted.