C&B accuracy/cylinder vs groove diameter

Muzzleloading Forum

Help Support Muzzleloading Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

phoenix511

40 Cal.
Joined
Jul 28, 2008
Messages
380
Reaction score
1
Several recent posts have discussed replica C&B pistol cylinder chamber diameter is less than barrel groove diameter, perhaps as much as 0.006" Some suggest enlarging chamber diameter to equal barrel groove to achieve best accuracy. Anyone out there done any testing on this matter? Before/after data, and best how to enlarge chamber diameter?
 
All revolvers shoot more accurately if the chamber diameter is a tiny bit larger than the bore diameter. If the bullet is less than groove diameter, high pressure gas can sneak past the bullet in the barrel. This can result in the bullet being pushed to one side and not revolving perfectly around its center of gravity and poor accuracy. It is true that an under size but very soft lead round ball will deform sufficiently as it enters the forcing cone of the barrel to seal the grooves, but it can't be very much undersize. The use of corn meal or cream of wheat filler under the bullet can also form a gas-tight plug behind an undersized bullet and help with accuracy by preventing blow-by. So, with effort you can wring accuracy out of a revolver that is incorrectly made, but why not get one that is?
 
Yes, that problem used to be very common, I think maybe less so today but it still crops up. I first encountered it maybe 35 years ago. I bought a Euroarms Remington style revolver just because I was very impressed with it in the store. The cylinder locked up so tight it was like one solid piece of cast iron. But when I shot it on paper the accuracy was dismal. After cleaning it and while the nipples were still out I rammed balls into every chamber and knocked them back out with a rod inserted through the nipple hole. I found that the balls, after being forced into a chamber would literally fall through the bore, not engaging the rifling at all.
I was working in a machine shop at the time and I was able to make up a tapered reamer to open the chambers to .452", which was .001" over the groove diameter. Thus modified that Remington shot several honest one inch groups at 25 yards with a short .454" wadcutter bullet and under two inches with .454" balls. I have since gravitated to shooting .457" balls in my .44 revolvers but no matter how large they may be before loading them they will come out of the cylinder at chamber diameter.
 


Write your reply...
Back
Top