Home Forums Hunting & Shooting Ask The Gunwriters Question From Reading Ken's "Burning Rates" Article in VH

Ken,

Enjoyed reading your article in the latest issue of Varmint Hunter titled Burning Rates - Solving The "Myth-Tery" . I have a few questions, if you don't mind. The first question concerns the table of "Burning Rates" that follows the article which I believe you stated came from Quick-LOAD.

What is the correct units for the burn rates associated with each powder? Is this correct?: in/sec per lb/sq in

Do you (or Quick-LOAD) have a similar table that has a measured value for the quickness of each of these powders? What are the units for quickness......pressure/time?, pressure/time/mass?, something else?

Ken, thanks for your time and keep writing these interesting articles.

HogWild

BTT

QuickLOAD lists these numbers only as the "Ba factor" for each powder listed and gives no indication that I can recognize as a unit of measure. If I were to rely on these numbers (which I do not), I would simply consider them as general indications or comparisons of relative quicknesses.

I have no table of burning rates. Several lists of relative quicknesses (called "burning rates") are available from a number of sources on and off the Internet. I do not rely on any of these lists, for reasons that I hope my article has made clear.

Given the widespread misuse and misunderstanding of the term -- with many people using and understanding it correctly -- it's next to impossible to know for certain what any specific use of it refers to.

I goofed -- overlooked and therefore didn't answer your question "What is the correct units for the burn rates associated with each powder? Is this correct?: in/sec per lb/sq in"

You'll find this answered on the first page of our article (middle column, in the last two full paragraphs):

"... For a typical nitrocellulose propellant powder in an average rifle cartridge, this burning rate is up to about 20 inches per second (20 in./sec).
"This is better stated as about 0.0004 inch per second (in./sec) for each pound per square inch (lb/sq in.) -- (about 0.0004 in./sec per lb/sq in.)...."

So you're right -- the unit of measure for the true burning rate (NOT relative quickness, which is another matter) is x in./sec per lb/sq in.

True burning rate is absolute, irrespective of quickness. Quickness is relative to some other powder, irrespective of burning rate. Bullseye is often given the arbitrary quickess value of 1.000, and the quicknesses of the other powders are then listed a fractions or multiples of this basic arbitrary reference value (if they're listed at all).

I had to really think about what the values in the table represented after I noticed RL-12 and RL-15 having a faster burn rate than RL-7. Your article is worded very well.....but I had a better understanding after reading it the 2nd time.

Thanks,

HogWild

� Since it's seldom possible to tell from context whether any given reference uses the term "burning rate" to refer to (a) the actual linear burning rates or (b) the relative quicknesses of the powders in its list --

� Since any "burning rate" list without any numerical scale gives no clue to how any two powders actually relate to each other in linear burning rate or in relative quickness --

� Since the relative quicknesses of two nearly identical powders can reverse themselves in different loads --

� Since I can never tell how (or how reliably) anyone has determined the rankings in any "burning rate" list --

-- I don't rest any reliance on them whatsoever.

Look at the list at the end of my article -- at the numbers in particular. Without the numbers, who'd know that Hodgdon H4227 and IMR 4227 have the same number (1.040)?

Or that Accurate 1680 and Hodgdon H4198 both rate 0.8650?

Or that VihtaVuori N130 and N133 both rate 0.7350?

Or that Ramshot Big Game and Vectan SP 9 both rate 0.5780?

Or that Accurate 2520 and VihtaVuori N135 both rate 0.5750?

Or that Alliant Reloder 15 and Norma 203 B both rate 0.5200?

Or that Alliant Reloder 19 and the old Norma 203 both rate 0.4500?

Or that Hodgdon H4350 and Hodgdon H380 both rate 0.4200?

Who wouldn't wonder or be confused by lists that reversed the positions of these pairs? If they rate the same numbers, why not reverse 'em on the list?

And who would guess that beneath the identically rated VihtaVuori N130 and N133, the next powder down (Hodgdon H4895) is rated 0.0144 lower (0.7350 - 0.7106)? And the next one down (Hodgdon H322) rates 0.6700 -- 0.0406 lower.

(And I'm just not real *&^%$#@! sure exactly what these numbers actually mean, in any real practical application.)