Burn rates, load density and stuff

Bill Daniel · July 29, 2014, 11:43 AM

If able and using small words why does IMR 4198 and IMR 3031 which are only 8 or so points away from each other on the burn rate chart have such different loads for the same velocity. For example, my 45-70 with a 405 gr. lead RNFP out of a 18 inch barrel takes 28 grains 4198 to hit 1225 fps at the muzzle and 38 grains of 3031. Of what value are burn rates? Are they at all related to load density?
I know to follow the recipes in my load manual and work up loads on all new powders but was just wondering if the burn rate charts have any value in reloading?
Thanks,
Bill

Bart B. · July 29, 2014, 12:14 PM

If I remember right, it's both the burn rate and the pressure curve shape. Two powders next to each other for burn rates; one has pressure rising fast at first then slower as the bullet is further down the barrel, the other is the opposite. Both may have the same peak pressure but one can have more average pressure for each .000010 second of time the bullet goes through the barrel in the .001200 second it takes. With two powders producing the same peak pressures, the one with the most average pressure shoots the bullet out faster.

The powder's expansion ratio effects both muzzle velocity and pressure curve shape and peak. That's the ratio of the powder volumn to the gas volumn it produces for a given bore diameter. The chemistry formulas across all the IMR powders are not the same; another variable to deal with.

I, too, don't don't know all about that stuff. The above is what a Remington field rep told me years ago about IMR powders. Ball powders may be different.

Unclenick; help!!!!!

Clark · July 29, 2014, 01:12 PM

4198 and 3031 are near optimum for how much powder will fit and how slow it can get to get the most velocity out of 405 gr 45/70 and keep the pressure at a minimum.
And that would be the goal with 30-06.
But with 405 gr 45/70 the recoil and Leading will be terrible at max velocity. So pressure might not be a driver.
So where most cartridges would probably be loaded with a narrow range of powders, the 45/70 405 gr cast gets loaded with a wide variety of burn burn rate powders.
CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information
I have shot 15 gr all the way up to 32 gr Unique in a Handi Rifle 45/70 with 405 gr cast bullets.
I have shot 40 gr 4895 in a Handi Rifle 45/70 with 405 gr cast bullets.

Both powder work well.

g.willikers · July 29, 2014, 01:35 PM

According to the physicist who used to live in our neighborhood, a specialist in Naval cannon ballistics, the study of propellents, density, weight, projectiles, pressure, temperature, wind effect, ship angle and (pant, pant) more will take you only so far.
In the end, he said, the way to be sure of the results is to just shoot it and see where it lands.
The rest is just theory yet to be put to the test.
So, the study of burn rates and such, alone, of small arms powders probably is not indicative of much at all.
The load data is, though.
Very much so.

mehavey · July 29, 2014, 03:06 PM

Simple "Burn Rate" without having all these other factors in consideration...

...is sorta like comparing a 98-lb girl doing a 40-yd sprint in the same timeframe as a 270-lb left tackle.

One runs into your arms.
The other absolutely creams you.

(On a more serious note, a little knowledge of "burn rate" is a very dangerous thing)

Magnum Wheel Man · July 29, 2014, 03:13 PM

I'll only claim enough knowledge on this subject to be dangerous...

so... I'll shut up & listen

madmo44mag · July 29, 2014, 03:17 PM

Quote:

I'll only claim enough knowledge on this subject to be dangerous...

so... I'll shut up & listen

To add - The more I learn the less I know!

Bill Daniel · July 31, 2014, 09:37 AM

Thanks to all. I guess in a world without loading manuals and load data the burn rate chart would let you know where in the spectrum of burn rates your powder was for your 380 or 416 Rigby but otherwise is of little value.
Bill

BigJimP · August 1, 2014, 05:35 PM

except everyone knows left tackles are 325 ...

/ but I like the analogy...

reynolds357 · August 1, 2014, 10:08 PM

Powders with identical burn rate can have tremendously different loading weights. The main difference is because different formulations of powder have different chemical potential energies per unit of mass.

RC20 · August 3, 2014, 01:16 PM

So why list burn rates at all?

If its an apples to an atomic bomb comparison it would seem its totally useless (or so out of context that needs all the other factors to be to be exactly that, useless) .

I hope there is a better explanation.

RC20 · August 3, 2014, 02:11 PM

This gets a bit off direct topic but I think its of interest from past posts in that it talks about powder effects on guns.

I am reading a book called Cannons, by DF Alsop (20 to 40 mm weapons)

Page 74 talks about propellants with the conclusion

1. Single based powders are the least erosive (by test not theory)

2. Double and triple based powders the most by as much as 20 times.

3. Triple based high energy nitramine (HEN) is in between 1 and 2.

I don't know if item 3 relates as I don't know we have that in rifle powders and the book is about semi auto cannon and they are into the 3300 fps area and may not apply but I thought interest.

The theory said flame temperature was the main factor but it turned out what gases were formed in conjunction with that and at least in cannons the single based powers had the lowest actually tested erosion (not necessarily a factor in what those type are after but may be applicable to what we do in rifles)

Marco Califo · August 3, 2014, 02:23 PM

Quote:

So why list burn rates at all?

Burn rates are relevant for powder selection, when you are not familar with a new powder. You can look up IMR 4064 and see that it is slower than H335. This is a clue that 4064 may work better with heavier bullets than H335. You still need to consult load data, where you will indeed find 4064 loads for heavier bullets. The same burn rate chart will also tell you that Bullseye, if it were available, would not be in the appropriate range for 308 or 223. The burn rate chart will also tell you that WC872 is very slow in comparison to 4064 or H335, and not suitable for 308 (ignoring the possibility of duplex loads, which is another topic altogether).
Can you live without burn rate charts? Yes. Is it useful to you? Only you can answer that. If it is not useful to you, so be it. I still want to look at them now and again.

Bill Daniel · August 4, 2014, 11:27 AM

Marco and Reynolds: Ken Waters in many of his Handloader articles used the burn rate for finding the appropriate powders for different bullets as in slow powders for heavy and fast powders for light projectiles. This did not relate to the charge weight but the appropriateness of the powder to the cartridge in question. He notes that both IMR 3031 and 4198 are excellent powders for the 45-70 and also confirms my finding that the loads are quite different for the same velocity. As in " different chemical potential energies per unit mass". And " This is a clue that 4064may work better with heavier bullets than H335".
Thanks again to all,
Bill

WESHOOT2 · August 4, 2014, 02:07 PM

I note I have eight 'burn rate' charts, and they all differ.

July 29, 2014, 11:43 AM	#1
Bill Daniel Senior Member Join Date: February 10, 2000 Location: Bowling Green, KY. Posts: 518	Burn rates, load density and stuff If able and using small words why does IMR 4198 and IMR 3031 which are only 8 or so points away from each other on the burn rate chart have such different loads for the same velocity. For example, my 45-70 with a 405 gr. lead RNFP out of a 18 inch barrel takes 28 grains 4198 to hit 1225 fps at the muzzle and 38 grains of 3031. Of what value are burn rates? Are they at all related to load density? I know to follow the recipes in my load manual and work up loads on all new powders but was just wondering if the burn rate charts have any value in reloading? Thanks, Bill __________________ Prosecute criminals to the fullest extent of the law and their weapons will become harmless. "Let us speak courteously, deal fairly, and keep ourselves armed and ready." Theodore Roosevelt 1903

July 29, 2014, 12:14 PM	#2
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	If I remember right, it's both the burn rate and the pressure curve shape. Two powders next to each other for burn rates; one has pressure rising fast at first then slower as the bullet is further down the barrel, the other is the opposite. Both may have the same peak pressure but one can have more average pressure for each .000010 second of time the bullet goes through the barrel in the .001200 second it takes. With two powders producing the same peak pressures, the one with the most average pressure shoots the bullet out faster. The powder's expansion ratio effects both muzzle velocity and pressure curve shape and peak. That's the ratio of the powder volumn to the gas volumn it produces for a given bore diameter. The chemistry formulas across all the IMR powders are not the same; another variable to deal with. I, too, don't don't know all about that stuff. The above is what a Remington field rep told me years ago about IMR powders. Ball powders may be different. Unclenick; help!!!!! Last edited by Bart B.; July 29, 2014 at 12:37 PM.

July 29, 2014, 01:12 PM	#3
Clark Senior Member Join Date: December 4, 1999 Location: WA, the ever blue state Posts: 4,678	4198 and 3031 are near optimum for how much powder will fit and how slow it can get to get the most velocity out of 405 gr 45/70 and keep the pressure at a minimum. And that would be the goal with 30-06. But with 405 gr 45/70 the recoil and Leading will be terrible at max velocity. So pressure might not be a driver. So where most cartridges would probably be loaded with a narrow range of powders, the 45/70 405 gr cast gets loaded with a wide variety of burn burn rate powders. CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information I have shot 15 gr all the way up to 32 gr Unique in a Handi Rifle 45/70 with 405 gr cast bullets. I have shot 40 gr 4895 in a Handi Rifle 45/70 with 405 gr cast bullets. Both powder work well. __________________ The word 'forum" does not mean "not criticizing books." "Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist. Are we a nation of competing ideas, or a nation of forced conformity of thought?

July 29, 2014, 01:35 PM	#4
g.willikers Senior Member Join Date: September 28, 2008 Posts: 10,442	According to the physicist who used to live in our neighborhood, a specialist in Naval cannon ballistics, the study of propellents, density, weight, projectiles, pressure, temperature, wind effect, ship angle and (pant, pant) more will take you only so far. In the end, he said, the way to be sure of the results is to just shoot it and see where it lands. The rest is just theory yet to be put to the test. So, the study of burn rates and such, alone, of small arms powders probably is not indicative of much at all. The load data is, though. Very much so. __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”

July 29, 2014, 03:13 PM	#6
Magnum Wheel Man Senior Member Join Date: July 26, 2006 Location: Southern Minnesota Posts: 9,333	I'll only claim enough knowledge on this subject to be dangerous... so... I'll shut up & listen __________________ In life you either make dust or eat dust...

July 29, 2014, 03:06 PM	#5
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,903	Simple "Burn Rate" without having all these other factors in consideration... ...is sorta like comparing a 98-lb girl doing a 40-yd sprint in the same timeframe as a 270-lb left tackle. One runs into your arms. The other absolutely creams you. (On a more serious note, a little knowledge of "burn rate" is a very dangerous thing)

July 31, 2014, 09:37 AM	#8
Bill Daniel Senior Member Join Date: February 10, 2000 Location: Bowling Green, KY. Posts: 518	Burn rates, load density and stuff Thanks to all. I guess in a world without loading manuals and load data the burn rate chart would let you know where in the spectrum of burn rates your powder was for your 380 or 416 Rigby but otherwise is of little value. Bill __________________ Prosecute criminals to the fullest extent of the law and their weapons will become harmless. "Let us speak courteously, deal fairly, and keep ourselves armed and ready." Theodore Roosevelt 1903

August 1, 2014, 05:35 PM	#9
BigJimP Senior Member Join Date: February 23, 2005 Posts: 13,195	except everyone knows left tackles are 325 ... / but I like the analogy...

August 1, 2014, 10:08 PM	#10
reynolds357 Senior Member Join Date: December 10, 2012 Posts: 6,165	Powders with identical burn rate can have tremendously different loading weights. The main difference is because different formulations of powder have different chemical potential energies per unit of mass.

August 3, 2014, 01:16 PM	#11
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,014	So why list burn rates at all? If its an apples to an atomic bomb comparison it would seem its totally useless (or so out of context that needs all the other factors to be to be exactly that, useless) . I hope there is a better explanation.

August 3, 2014, 02:11 PM	#12
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,014	This gets a bit off direct topic but I think its of interest from past posts in that it talks about powder effects on guns. I am reading a book called Cannons, by DF Alsop (20 to 40 mm weapons) Page 74 talks about propellants with the conclusion 1. Single based powders are the least erosive (by test not theory) 2. Double and triple based powders the most by as much as 20 times. 3. Triple based high energy nitramine (HEN) is in between 1 and 2. I don't know if item 3 relates as I don't know we have that in rifle powders and the book is about semi auto cannon and they are into the 3300 fps area and may not apply but I thought interest. The theory said flame temperature was the main factor but it turned out what gases were formed in conjunction with that and at least in cannons the single based powers had the lowest actually tested erosion (not necessarily a factor in what those type are after but may be applicable to what we do in rifles)

August 4, 2014, 11:27 AM	#14
Bill Daniel Senior Member Join Date: February 10, 2000 Location: Bowling Green, KY. Posts: 518	Burn rates, load density and stuff Marco and Reynolds: Ken Waters in many of his Handloader articles used the burn rate for finding the appropriate powders for different bullets as in slow powders for heavy and fast powders for light projectiles. This did not relate to the charge weight but the appropriateness of the powder to the cartridge in question. He notes that both IMR 3031 and 4198 are excellent powders for the 45-70 and also confirms my finding that the loads are quite different for the same velocity. As in " different chemical potential energies per unit mass". And " This is a clue that 4064may work better with heavier bullets than H335". Thanks again to all, Bill __________________ Prosecute criminals to the fullest extent of the law and their weapons will become harmless. "Let us speak courteously, deal fairly, and keep ourselves armed and ready." Theodore Roosevelt 1903

August 4, 2014, 02:07 PM	#15
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	science vs magic; we don't know enough (yet) I note I have eight 'burn rate' charts, and they all differ. __________________ . "all my ammo is mostly retired factory ammo"