Unless they've changed it in the last 9 years, the Pietta 1861 Colt has .367 diameter chambers which should work nicely with .375 diameter balls.
(Back in the old days, 9 years ago, Dixie Gun Works shows the chamber sizes for the C&B revolvers it sold.)
O no I punched in the wrong numbers sorry I meant to say .375 but Pietta calls for .376 ball,maybe I’m just use to my 44”s being a good tight fit compaired to the 36cal.Maybe I will try the .380 ball. Thank you for the input.Yes Dixie GW still shows the chamber size for most of the revolvers.
Go for .380 especially if you plan on buying a mold. As someone pointed out, they offer more bearing surface plus the will ensure a gas tight fit. Original conicals were typically .380 or larger.
I have a Pietta 1861 (too) that I’ve been shooting regularly for 23 years. 1997 [BI]. I started out using .375 balls for a lack of knowing any better but it soon became clear that those were way too small. The balls would ‘walk’ forward in the chambers while shooting. Switched to .380 and problem solved. Its accuracy really improved, too. With .380’s it became a tack driver. I invariably use .380 in all of my thirty-sixers.
Being a history person I sort of regret that extra one half inch of barrel but it handles and balances great and over the years I’ve learned to really appreciate that thang.
Here is he test.
Clean and lightly lubricate a chamber or two. Remove the cones and dry ball those chambers.
Use a brass punch to push out the ball. A brass punch is important because if you use a steel one it is possible to fudge up the threads and convert the cylinder to a pencil holder.
Check the sealing band on the ball. My '61 Navies shoot .375" balls and I have yet to have anything go wrong after several hundred rounds.
Hold center
Bunk