Cartridge efficiency value

[geordiesniper]

Many years ago when I first got into Benchrest I read an article about Cartridge Efficiency Value in a magazine which I think was Precision Shooter. It is a formula to work out what powder charges should be used to give the same muzzle velocity in various temperatures. I am not sure if the CEV formula was only for 6PPC or could be utilised for other calibres. Has anyone got any information on the formula and if it can be used with other calibres please. Good shooting to all.

 

[spclark]

Be interesting to see what response you get to your query.

I don't recall seeing that article but I didn't get with the program until late in '02, PS subscription started a little after.

Propellants introduced since those days that show less temp sensitivity might make such a formula irrelevant or at least less valuable than before? I dunno....

Still, be interesting to see how it was intended to work, may be even improved upon knowing what we know now.

 

[geordiesniper]

Be interesting to see what response you get to your query.

I don't recall seeing that article but I didn't get with the program until late in '02, PS subscription started a little after.

Propellants introduced since those days that show less temp sensitivity might make such a formula irrelevant or at least less valuable than before? I dunno....

Still, be interesting to see how it was intended to work, may be even improved upon knowing what we know now.

Hi, you may well be correct as I am sure it was in 1992 or thereabouts but not sure of the magazines title. After some thought I am sure that it was based upon a particular powder namely Viht N133 and the cartridge was 6ppc. So my intial comments about utilising the formula for say .284 Win would not work.

 

[Dusty Stevens]

In 92 i doubt it was about n133 but probably about a 6ppc and either 322 or 8208 or t32

 

[Sheldon N]

Some info here from Hodgdon on temperature vs velocity with a few different powders and cartridges.

https://www.hodgdon.com/smokeless/extreme/page3.php#top

 

[spclark]

In 92 i doubt it was about n133 but probably about a 6ppc and either 322 or 8208 or t32

And that's NOT the new IMR 8208XBR either (conspicuously free of temperature sensitivity by design too!) rather what came before. The original 8208's not been seen lately except maybe in some pull-down stuff available three or four years ago.

 

[riflewoman]

I never read the article but I would think that the Powley Computer and the foundational equations for that device would be very similar. Most rifle cartridges are best when loaded between 80 to 90 percent of charge weight to case volume as weight of water. The bullet weight tends to skew the powder charge to faster or slower in "burn rate" with heavier bullets tending to push the burn rate to a slower powder. In its day there were several limits but it did give decent data to start from if you were careful.

 

[spclark]

I never read the article but I would think that the Powley Computer and the foundational equations for that device would be very similar.

Good to know, thanks!

I've added a link in that quoted portion of your post. Before I read that I'd been unaware of this calculator.

 

[Marksman63]

Is this related to QuickLoad's ballistic efficiency factor?