I am looking into having a single point cut-rifled 45 caliber barrel made for a 45 Colt SAA that will be set up to shoot .454" cast bullets. All of my research and personal experience indicates that cast bullet accuracy is best with bullets .001" over groove diameter. Looking at Krieger barrels caliber list, they make their 45 caliber handbun barrels with a .450" groove diameter, and .442 bore diameter. They told me on the phone that they can cut the groove depth to .453" like I want, but they can not increase the bore diameter without spending a whole lot of money. This would leave me with rifling depth of .011". The rifle depth of most of their barrel's is .008". Though Krieger's 44 magnum barrels have a rifling depth of .012". I will be shooting bullets with BHN's as low as 9 (Wheelweight alloy) and as high as 16 (Lyman number 2 alloy). Do you think that the extra .003" of rifling depth will make any difference? I am looking for the finest accuracy possible. Can fire laping reduce the bore/land diameter while leaving the groove diameter the same? Might fire lapping give me a magical tapered bore? Does anyone know of a barrel maker who makes single point cut-rifled barrels with a .453" to .454" groove diameter and bore diameters that are .008" less than groove diameter? Any informed comments would be greatly appreciated.

Matt:

First of all, the standard rifling is .008" on the diameter, the actual depth of the grooves is .004". On the .442/.453 barrel you describe the rifling would be .0055" deep, which does not sound quite as scary.
I assume that there is something about the cylinder that makes you want to shoot .454" bullets instead of getting a standard barrel and shooting .541" bullets. It has been said that the key to revolver accuracy is to match the bullet to the throat. It would be an interesting experiment.

Glenn

HST, my mistake. You are correct. I forgot to split the difference for the rifling depth. The reason I want a barrel with .453 groove diameter is because I want to be able to shoot both .454" factory loads and two particular handloads containing .454" bullets (RCBS 45-270-SAA and Lyman 454190). Winchester and Remington's traditional style factory loads for the 45 Colt are loaded with .454" bullets, and the two custom bullets mentioned, cast almost right at .454" straight from the mold.