Lead ?

[Kurt]

Wayne.

A little back ground on my .40-64 Browning BPCR.
I picked this rifle up used at a very good price. Shooting it when I first got it the would throw shots all over the paper. I made a chamber cast and found the throat was oval several thousands like a undersized pilot was used. You could even see it looking at the cast.
I had Manson make a throating reamer with a 4 degree/1.5 degree compound reamer from the chamber wall. That cleaned out .236" of the bad throat, freebore and all. This concentric taper improved the accuracy shooting PP or GG bullets and made this a fine accurate rifle.
I don't consider that concentric throat a PP throat, I call it a lead bullet throat. Check out the match .22 rimfire throats. They are a lot flatter then my 4 degree. They run as flat as a 1.5 degrees and they don't use a patched bullet.
I like my patched bullets couple thousands over bore diameter, this pushes the ogive tight into the concentric throat for perfect alignment. It is a plus for a PP bullet over a GG. A GG the way it is now designed with a reduced step from the shank to the ogive it gains nothing as far as aligning the bullet to the bore unless you cam the driving bands into the lead and this is lost if the bullet is seated in the case with a bunch of runout. This is were a action like the 44-1/2 Stevens where the block will cam the tight bullet into the lead. This is ideal for a groove diameter PP bullet where you can seat that bullet like a bore diameter patched bullet and get all of the benefits of a groove diameter patched bullet.