Is there a formula for calculating the optimum case volume for a given bore size?

Interesting question, Doug. What performance characteristics would you be looking at to detrmine what is optimized ? Just arriving at the parameters potentially indicated would make an interesting discussion.

Do you have some measurement in mind? roger

out of curiosity, if the formula exists, how would case shape be factored in, as that has an effect on performance.

yeah, I got time on my hands

"There is no set rule or way to determine the proper or maximum case capacity, at least as yet"

P.O. Ackley
Hanbook for Shooters and Reloaders
1962

OK guys, whatever happened to computer modeling?

I have an old (1980's vintage) computer program I put together, about then, to help determine capacities of various cylinders with compound angles and diameters as those found in the bore and chamber of a high powered rifle, to help figure expansion ratios (ER) and other cool crap. I may still even have the computer (Commodore 64) that ran it. I will have to brave the black widows to have a peek.

If you know the ER you wish to achieve and the bore diameter, it may be possible to work the program backwards to find the optimum capacity to put you in the ball park of the desired ER.

You might Google "Homer S. Powley" and see if you can find any of his stuff. Or, you might check this out. http://www.loadammo.com/

craigster

quote:

"There is no set rule or way to determine the proper or maximum case capacity, at least as yet"

P.O. Ackley
Hanbook for Shooters and Reloaders
1962

I have that book too. You would think that in 45 years someone would have come up with something.

Quite often we read where a gunrag writer states that a certain case is optimum for that bore. They are just probably pulling data out of their ass as usual because they never back up that statement.

Malm...ah I mean Westpac Blackwidow bites aren't that bad. Just get to the doc fast! When I was bit I was only laid up for four days.

There is no "optimum" anything about cases. Everyone has their own wants, needs, and desires, and thankfully we have a cartridge to fill just about anyone's idea of "optimum."

The whole idea o f"optimum" and "efficient" got rolling when Winchester and Remington started trying to sell their short magnums. They are less powerful than the longer magnums, so they said they are better because they are "more efficient." What a load of garbage!

When looking at cases, pick one that gives you the power you desire and that will be "optimum" for YOU. And rememebr, forget all of the gunwriter BS about "short and fat" being better. All that matters is case volume. Bigger volume, faster bullets. Smaller volume, slower bullets. All of the garbage that is regurgitated by almost all of today's gunwriters has done more to spread outright lies about guns than anything else. Sarah Brady has more credibility than just about anyone you would read in Guns and Ammo and Shooting TImes.

Case in point-a few months ago some gun magazine showed up in the mailbox. Craig Boddington was talkiing about the new .308 TC cartridge, which is smaller than the .308. He sait id had less volume than the .308, "and that's a good thing" were the exact words he used. That is an outright lie and I do not believe that he is ignorant enough to actually believe that. A smaller case loaded to the same pressures will be slwoer tahn the larger case at the same pressures when using appropriate powder in each. The .308 WIn is faster than the new TC round.

If you want "efficiency," then get a .30 Carbine. No other .30 caliber can touch it.

SO to sum up the answer to your quaetion, there is no formula, as each of us has a different idea of "optimum." Get the case that produces the power level you desire. And remember, cartridge cases are not exempt from the laws of physics and thermodynamics. There is now majic, voo doo, or free lunch.

quote:

Originally posted by Marc_Stokeld:
There is no "optimum" anything about cases. SO to sum up the answer to your quaetion, there is no formula, as each of us has a different idea of "optimum." Get the case that produces the power level you desire. And remember, cartridge cases are not exempt from the laws of physics and thermodynamics. There is now majic, voo doo, or free lunch.

IMHO, best intelligent answer so far. roger

don, this article backs up what has been posted to some degree
http://www.encyclopedia.com/doc/1G1-87564350.html