1851 bullet size

[Colt Fanning]

Hi,
I have an 1851 pieta sheriff's model that shoots rather poorly.  The cylinder sizes the bullet about .004 in. smaller than the
barrel.  Could this be the cause?  What is the correct bullet size for a cap and ball?  1 to 2 thousands oversize?  I replaced the
barrel but got only slight improvement.
Regards
Colt

[Pettifogger]

Almost every Pietta I own has chambers that are well under bore size and they all shoot just fine.  Just make sure you are using a pure lead ball and enough of a charge so it upsets when it hits the forcing cone.  Doesn't matter what size the bullet is, once it is shoved into the chamber it is chamber size.  Unless your chambers are well under bore size don't worry just shoot it and have fun.  You didn't say what caliber you have, but if its a .36 most use a .375 ball.  If it's a .44 you can use a .451 in the Pietta, but I use .454 so I can use the same balls in my Ubertis.

[Fingers McGee]

Almost every Pietta I own has chambers that are well under bore size and they all shoot just fine.  Just make sure you are using a pure lead ball and enough of a charge so it upsets when it hits the forcing cone.  Doesn't matter what size the bullet is, once it is shoved into the chamber it is chamber size.  Unless your chambers are well under bore size don't worry just shoot it and have fun.  You didn't say what caliber you have, but if its a .36 most use a .375 ball.  If it's a .44 you can use a .451 in the Pietta, but I use .454 so I can use the same balls in my Ubertis.

+1

[44caliberkid]

First off, I concur with the above two posters.
  Second, changing the barrel won't help.  You would have to slug the barrel and determine the groove depth.   Then ream out your cylinder mouths to match, then use a ball that's a few thousandths bigger than that.   This is if you want competitive, target grade accuracy.   For CAS matches or recreational shooting, the first two suggestions, mainly using soft, pure lead, will do you fine.