Home Forums Hunting & Shooting Ask The Gunwriters Powder burn temperatures

If there’s been a study on the flame temperature of smokeless powder, is there a chart showing the differences?
In particular, in shooting say “lever action silhouette” or some other “game” where there are multiple rounds shot, burning temperature may affect the POI of the last few rounds.
When I test ammo, I’ll often let the barrel cool. But in the field or at a competitive game I will shoot as fast as needed.

Finally, double base powders, do they burn hotter?

Sure see e.g. emphasis added to material at http://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/

For your purposes I might fuss with Tempilaq or otherwise worry more about barrel temperatures than bomb temperature. I'll leave it to you to Google for more information on nitro cellulose or nitro glycerin powder temperatures. I don't know that such information is collected all in one place but the Gun Gack book and others by the same author - John Barsness - mention such at least in passing.

In general, double-based powders do burn a little hotter than single-based powders, but exactly how much warmer depends on the amount of nitroglycerin. One Australian military report (the most detailed I've found on barrel erosion) points out that the nitrogen in nitroglycerin actually hardens the surface of barrel steel a little, counterbalancing the effect of higher temperatures.

Apparently the big factor in bore erosion isn't the exact temperature of the powder burn, but the amount of powder and the duration of the burn. This is why large powder charges for the bore-size fry barrels quicker, and also probably why shooters using some of the newer ultra-progressive-burning powders report quicker bore erosion.

Superb answer, Roomie, and, as usual, totally spot-on.

kd

Thanks, 'dude!

I guess it will take a little trial and error on determining POI changes depending on different powders.

One of my favorite powders for several low pressure cartridges is 4744. An aquaintence suggested using another powder to lesson the heating effect of the powder. In lever action silhouette, obviously the POI change wouldn't be a significant factor I suspect, since it is with iron sights, off-hand and with rifles capable of 1 MOA at best.

But then there's those darn prairie dogs. Heating of the barrels can and usually is significant. (I'm guilty of burning out a barrel during the "heat of the battle" so to speak.) Some rifles don't change POI much upon heating, while some do.

That spreadsheet Clark shared, includes Moly coating. I wonder if Dyna Bore Coating would have a similar affect as Moly since I've chosen to use Dyna Bore and not to use Moly.

IIRC ball powders are double based. Can ball powder manufacturers use additives to reduce the burn temps? I ask because I've gone through many pounds of W748 that had a lower flame temp mention on the label.

https://wwpowder.com/748-2/

Yep, all spherical powders are double-based. (Sorry, I automatically call them "spherical" instead of "ball," because Winchester trademarked the term "Ball" after developing the process. At least one magazine attempts to avoid any legal problems by using the generic term spherical, instead of Ball.)

Powder manufacturers often are pretty closed-mouth about real details, though once in a while they slip up and say something other than the basics. Haven't heard about that one, but they might use a coating that helps it burn cooler.

In a gas, temperature and pressure are "people scale" manifestations of the same micro scale thing: speed of molecules. More pressure = higher temperature.

Can’t make energy without heat.

Run lighter lower pressure rounds if you're worried about barrel heating. I wouldn't be looking at what powder I used so much as how much powder I was burning per round.

which powders do you mean when you say "ultra-progressive-burning" ?

thanx

The allegation is that a powder can produce the same velocity as another without as much heat.

General comment: Temperature and heat are not the same thing.

T

Yup





Same temperature

Quickload lists burn temperature, but I believe it is the so called bomb test (Closed Cylinder) so may not apply the same in a cartridge. I have also read ball powders are less abrasive than stick and reduce wear from un-burnt powder in the throat. This might just be speculation.

Do higher velocities reduce barrel time and somewhat compensate for heavier charges and erosion?

If you want really cool burning powder use black powder.

Real black powder is cool.

For a challenge go PD shooting with black powder. I don't have a flintlock, but a percussion with FF works.

Pick a bullet of a given diameter and weight and lets say you want to push it 3000 fps. You'll need a given cartridge case size to achieve that velocity, and will burn a given amount of powder to achieve that. Your barrel will only last so long. If you want to push the same bullet 3500 fps, you'll need a larger case burning more powder and your barrel life will be shortened.

What you can use is barrel length to increase the accurate life of a barrel. A .308 with a 26" barrel is going to have a significantly longer barrel life than a 300 win mag cut to whatever length matches the velocity. You have less dwell time in the barrel in the 300 win mag, but a barrel will last way longer with a nominal 45 gr powder charge in the the .308 than a nominal 70 gr charge in the win mag.

A larger powder charge headed down the same sized hole will be more corrosive, all things being otherwise the same.

Think of it like sand.

I there's a limit on how much sand I can force down a opening before the opening wears out. Driving more sand and at a higher velocity down the opening accelerates wear.

So, same diameter (.308) with more powder (300 Win Mag) will always wear the throat faster, no matter what type of powder, even if you "loaded down" the 300 Win Mag to 308 velocities.

Erosive