I recall seeing a chart a few years ago that listed optimum barrel length based on chamber volume. The ratio was in the neighborhood of the bore volume being ten times the chamber volume to properly use expanding gas from burnt powder. Shorter than indicated was more muzzle flash and longer slowed the bullet. Does any one have or know where to find this or was it just someones stab at seeming scientific? The only other thing I've seen like this was one of the magazines (American Rifleman?)cut a 22LR barrel down in 1/2 inch steps to determine optimum length by velocity. They found it to be just under 16 inches.

Hello Sam,

I don't remember where I read this, but the "expansion ratio" that I recall as being optimal was 9 to 1 (very close to your 10 to 1). Might have been in "Cartridges of the World"?

Regards, Bill

how does one get the chamber volume?

Krag & Sam

Most ballistic calculators use the case capacity in grains of water rather than the chamber volume. (The chamber is partially filled by the brass case) Fill the case to the base of the bullet. You then measure barrel length from muzzle to base of bullet and factor in the bore diameter to obtain bore capacity. I think expansion ratio is a simple math calculation from there.

The old Powley Computer For Handloaders was a slide-rule type devise that calculated expansion ratio but the modern computer programs do the same thing much faster.

Ray

I still like the antiquated idea of loading some and seeing which one shoots the best. Stupid idea I guess but works for a lot of people.