All those burn charts are nice, but many powders are about equal in burn rate. I'm usually working on loads that I have to work up from scratch and would like to see a burn rate chart of powders with say, a value based relative rates. Anyone seen one of those?

Greg

quote:

...value based relative rates.

I'm flummoxed. Could you further explain exactly what data you are looking for?

Powders flip flop in burn rate depending on the powder lot, case they are used in and the pressure they are loaded to. Even the bullet weight has some effect.
The only values that I know of are the closed bomb tests.

The Norma manual has a burnrate chart based on how the powders perform in a 308w

Kimmo

I've seen a chart exactly like you're looking for,,,,,it had Win 760 and H-414 on the same line.....not one ahead of each other.....be patient...someone will know where it is.....did you check Steve's pages?

Page 2 of the Vihtavouri reloading guide has one...with the powders aligned proportionally in approximate burn rate. Take a look.

Here it is for download, in PDF format

I wouldn't expect to find, nor would I trust, anything more precise because of the afore mentioned variance from lot to lot and cartridge to cartridge.

Yeah, Steve's pages has one...

http://stevespages.com/table3.html

Scroll down and look for powder burn rates button...

It's a bit scrambled but pretty complete..

Ken....

Not sure what you mean by "value based relative rates" either

ADI has a good chart. The Vihtavouri one is good too

http://www.adi-limited.com/handloaders-guide/equivalents.asp

quote:

Originally posted by onefunzr2:

quote:

...value based relative rates.

I'm flummoxed. Could you further explain exactly what data you are looking for?

Well, we all know bullseye is faster than red dot because it's above it in the ubiquitous powder burn rate charts that list their position in that regard. But how much faster is it? Is there anyplace that puts a value in it or assigns a number indicating it's relative speed? Of course lots vary slightly. That's been the case since I started reloading over 4o years ago. Aging or rough handling can also affect the burning rate.
What I'm looking for is a value, based on actual burning rates. So, if I wanted to go to a slightly faster powder, I could do it accurately and not just assume that because it's 2 positions higher on the chart, it's not too much faster. Still looking I guess. Any help appreciated.
Thanks,
Greg

quote:

Originally posted by GSP7:
Not sure what you mean by "value based relative rates" either

ADI has a good chart. The Vihtavouri one is good too

http://www.adi-limited.com/handloaders-guide/equivalents.asp

great chart

quote:

Originally posted by CDH:
Page 2 of the Vihtavouri reloading guide has one...with the powders aligned proportionally in approximate burn rate. Take a look.

Here it is for download, in PDF format

That's the best one I've seen, CDH, Thanks for the link.
Greg

If you have a copy of QuickLOAD, you can simulate a bomb calorimeter test by "firing" a low loading density charge under a 200 lb bullet. Look at the plots of pressure rise rates and find the slope. I did this with the IMR powders and got relative numbers close to those reported in the old NRA Handloading book.

You can`t assign a fixed burn rate to powders as they vary in rate depending on the pressure they are being burnt at as noted above. Most powder manufactures assign a burn rate number to THEIR powder relative to one of their other powders -VV relates their N300 powders to N110 which is assigned a value of 100 for this purpose. Alliant I believe uses Bullseye as their base for rateing burn. These are all only valid when done in a caloric bomb test and the rate will vary under different conditions.

Of course you're right, but it can be done from a relative standpoint (all things being equal) which is apprently what Vihtavouri did with their very informative chart. Good for adjusting, or working up new loads under a given set of conditions.
Thanks for all the input here folks!
Greg

Nexplo Bofors test in the Norma manual shows the powders pressure and speed in % relativ to 308w with 143gr fmj and 43,2gr imr4350 as the 100% (all shot in the same caliber).

I have seen a chart like brayhaven is talking about.

The powders a listed according to a numerical rating.

Like the fastest powder is rated and the next fastest powder is rated number 99, going in descending order.

Sorry but I dont't know anyway to find such a chart or even if any powder companies list powders that way.

I must agree it would be much more simple if the ratings were Norma R1 #1, Alliant Power pistol #46 etc.

Some folks do reference powders by a # and say the chart starts out with Norma R1 having a relative burn rate of 100, so whats the relative burn rate of IMR4350? 80?

But I see a sticky wicket in this thought train also. When ever they change forulations it would screw up the tra la la.

But I have heard through the grapevine that whenever a formulation is changed it has to be within 5% variations of the previous lot of that particular powder.

I guess that is why those in the know always start at 10% lighter loads when changing components including powder charge.

I don't have any friends at any of the major powder producers so I can't substantiate any of this info.

Any of you know any folks in high places?

Best wishes, Bill

All the various burn rate charts have some powders in different order anyway

quote:

Originally posted by GSP7:
All the various burn rate charts have some powders in different order anyway

I agree, but do they change all that much?

I find many of the burn charts a bit confusing. Take a look at VV N-130 for example. Ramshot, Sierra and GS Custom all have N-130 in the 5744, W 680 and Lil-Gun catagory, while Hodgdon, VV, and Steve all have it rated similar to IMR 3031, AA 2015 and H322. To me that seem like a pretty far spread.