Looks like my birthday present needs a little work

[oldandslow]

Got out to the range Memorial Day and tried it out with 23 grains of FFFg and .451 round balls. Got some pretty good groups, especially considering the sights and the age of my eyes. Went back this morning and went up to 28 grains and it started shooting patterns instead of groups. Looks like the chambers are too tight for the bore and the larger charge is probably causing the ball to skip the rifling. Anyway that's the conclusion I came to after slugging the bore and measuring the chambers. The manual says use .454 balls but they are too large for the chambers and would be shaved down to the same diameter the .451's are when seated even if I could seat them. The .451 I pushed thru the barrel didn't contact the bottom of the grooves. A .454 ball, although very difficult to start, did contact all the rifling. Anyone had any experience with something like this? Don't have any idea where to find a gunsmith in this area to ream them. 

[simonkenton]

Have you fired a group with the .454 balls?
Yes they would be shaved down to the same size as the .451, but, there would be more lead in contact with the rifling, there would be a wider flat spot on the side of the larger ball.
I would try those .454s since that is what your manual says to use.
My theory is, the bigger the better, my manual says use .454 balls and I use .457

[oldandslow]

No, I haven't. I understand what you are saying about more surface in contact with the rifling. I attempted to load .454 balls but quit. The rammer isn't going to stand up to the force required to seat the balls. The diameter of the chambers requires too much lead to be shaved off the .454 balls. It shaves a pretty good ring off the .451 diameter balls as it is.

[NickSS]

I do not know what gun you are talking about but generally if a 451 ball seats too easily there is a potential for a chain fire as the chamber is not sealed.  I load a lot of balls in revolver chambers and generally they take either 451, 454 or 457 diameter balls.  I generally load the next size up ball to make sure I shave lead when seating the ball.  If your balls are too hard to seat what did you cast them from?  You should only use soft nearly pure lead in a cap and ball revolver.  My brother cast up a batch one time from wheel weights.  They were darn near impossible to seat in a revolver with the loading lever.  My piatta 1858 remington has had the chambers reamed up to .454" diameter and I load 457 balls in it.  This was done to get rid of some rust that started in the chambers due to not cleaning it promptly after shooting during wet weather.  I used a reamer I bought special for the job.

[oldandslow]

I do not know what gun you are talking about but generally if a 451 ball seats too easily there is a potential for a chain fire as the chamber is not sealed.  I load a lot of balls in revolver chambers and generally they take either 451, 454 or 457 diameter balls.  I generally load the next size up ball to make sure I shave lead when seating the ball.  If your balls are too hard to seat what did you cast them from?  You should only use soft nearly pure lead in a cap and ball revolver.  My brother cast up a batch one time from wheel weights.  They were darn near impossible to seat in a revolver with the loading lever.  My piatta 1858 remington has had the chambers reamed up to .454" diameter and I load 457 balls in it.  This was done to get rid of some rust that started in the chambers due to not cleaning it promptly after shooting during wet weather.  I used a reamer I bought special for the job.

It is an 1860 Army replica made by Pietta. The .454 balls aren't too hard, they are just too big. I tried balls made by Hornady and my own cast from pure lead. I save the wheel weights for centerfire. All my lead supply is labeled with a magic marker so I can tell what is what. Not only am I old and slow, I'm forgetful too.  Did you notice in my post that I said there was a pretty good ring of lead shaved off the .451 balls when I loaded them. The chambers are undersized for the bore. If I did force the .454 balls into the chambers they would be undersize for the bore then. The chambers need reamed. Mind telling me where you got your reamer? I smear Crisco (nasty stuff) over the balls after loading to make sure on the chainfire thing and I've never had a chainfire and I've been shooting a couple of BP revolvers since the 70's.

[Nobade]

It's pretty common with repro C&B revolvers to have them come with chambers smaller than the groove diameter in the barrel. It's not a big deal to ream the chambers to the correct size, and accuracy will be greatlt improved. Just like a cartridge firearm, the bullets can be bigger than the groove dia, but not smaller or it won't work well.

[madcratebuilder]

Most Pietta's I see have .445 chambers, to small for .454's.  I ream the chambers to .451+ and use .457 rb.  Works for me.

[fr3db3ar]

I have a Pietta Old Army 44.  I haven't measured but I use a 454 ball and it seats decent.  I use lubed pads between the ball and powder and don't have chain fires.  I've heard there is a lot more chance of chain fire from a loose fitting cap than past the ball.  I get decent accuracy using 25 grains fff All American.  I'll be stepping it up to 30 for hunting.