Handbook for Shooters and Reloaders

[Andy]

I have both volumes of his work and they are well worth while reading. Keep in mind that Mr. Ackley (like Rocky Gibbs) had some commercial interests and many of his claims concerning performance increases from "improving" a cartridge have since been debunked. His claim that straightening the taper on cartridges reduces bolt thrust has possibly generated the most controversy. In fact bolt thrust is a simple product of case head diameter and pressure, having nothing to do with the shape of the case, understanding that in a dry (non-oiled) chamber, the brass grips the chamber walls, and only the unsupported part (the casehead) stretches back against the bolthead. That doesn't mean that less taper and sharper shoulders doesn't decrease brass "flow" (and hence increase brass life), just that the notion of a tapered cartridge "squirting" out of a chamber is a myth.