powder equivalency chart?

[mattri]

Does anyone know of a chart showing realitive powder charges between powders?

For example 43grns of IMR 4350 is equal to xxgrns of IMR 4064.

Does such a thing exist?

 

[zullo74]

I never saw such a chart, but this can be easily figured out with software such as Quick Load.

 

[Steve Blair]

It is probably too dependent upon powder density, single or double base, cartridge volume, pressure, bullet weight, etc. The closest, as you know, is a burn rate chart.

 

[watercam]

It does not translate that way with every cartridge. Best bet is several reloading manuals (should have at least two anyway) and compare within the cartridge you are interested in. I am partial to the Nosler manual myself as the results there seem to mirror most of my results on the range but they are all pretty good.
There are burn rate charts that have powders in their relative burn rates but they do not give equivalent values.
Mike T.

 

[Shootndig]

I don't believe any such chart exists. If it does, it would be cartridge AND bullet weight specific, and the common denominator or linking factor would be the pressure generated by those powders in that cartridge, with that bullet, in that test barrel. In my mind, to attempt to make any other type of equivalency any broader than that is flirting with disaster. Just my .02

 

[Laurie]

I don't believe any such chart exists. If it does, it would be cartridge AND bullet weight specific, and the common denominator or linking factor would be the pressure generated by those powders in that cartridge, with that bullet, in that test barrel. In my mind, to attempt to make any other type of equivalency any broader than that is flirting with disaster. Just my .02 [Shootndig]

+ 1 on that. Burning rate charts are exactly what they say - rankings according to how 'fast' or 'slow' the powder burns in the early stages of ignition and charge-burn in labortaory conditions using things like the 'closed bomb' device. There is much more to propellant performance than this alone. As most manufacturers point out, burning rates vary according to cartridge characteristics, so that the relative order can change, sometimes appreciably depending on the application.

Trying to guesstimate data for a powder with no data for the cartridge through interpolating loads from using a burning rate chart allied to loadmaps for other 'similar' powders is potentially very risky in some applications. Even keeping charges right down may not be safe if the powder's characteristics are all wrong for the cartridge as sometimes happens.

QuickLOAD is a really useful tool for looking at unlisted combinations, but although its results should be safe if used with caution, they may still not give acceptable results in practice. Undesirable results I've obtained include poor accuracy, large MV spreads, acute barrel copper fouling, excessive muzzle flash and blast, sometimes all of these in combination!

We're in a quandary when the powder manufacturer omits what looks like a good prospect for a particular cartridge and bullet weight / type. Is it because of a decision to limit testing on time and cost grounds, or because it was tried and didn't work? In most cases, we now have such a large choice of powders and avilability of data, that we don't have to step 'out of the box' and experiment. If we do, we have to understand the possible risks and pitfalls.

Laurie,
York, England