What does BH209's progressive burn really mean?

[tpcollins]

I'm trying to understand how a progressive burning powder differs from whatever Triple 7 is. What I've gleaned from BH209 is the pressure builds over times versus Triple 7's pressure is all at once ??

So with Triple 7, you have 100% pressure all at once starting to push the bullet/sabot down the barrel whereas with BH209, the pressure continues to build in increasing amounts while the bullet/sabot is moving down the barrel? And why is the progressive burn method preferrred? Thanks.

 

[quigley]

Because with a progressive burning powder such as BH209 you can get the same velocitys as 777 with less powder. But ignition can be sensitive with certain primers and BPs. Not to mention you can shoot all day and no swabbing.

 

[tpcollins]

Thanks quigley but that wasn't exactly what I was looking for. I stumbled across this article and it answers my question pretty well - I think:

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Black powder is composed of charcoal, sulfur and potassium nitrate. It burns rapidly at a linear rate regardless of the pressure but produces less maximum pressure than does modern smokless powder. and, yes, it does produce clouds of smoke when it is used as a gun powder.

Smokeless powder is composed of two basic materials. One is nitrocellulose and the other is nitroglycerine. Some smokeless powders are made of only one of these materials and is called a single base powder. Others are composed of a mixture of both components and are called double based powders. The reasosn for using mixtures of the two components is to control their burning rates. Faster burning powders are used for shotguns and handguns. The slower burning powders are used for rifle powders.

Smokeless powders are all progressive burning powders. That means that as the pressure within the cartridge increases, so does the burning rate. It produces a more gentle acceleration than does black powder and achieved much greater final pressures and higher total velocities than will blackpowder. Blackpowder burns at the same rate regardless of the increasing pressure. The maximum pressure is reached more quickly but is significalntly less than smokeless powder. These lower total pressures of black powder are the reason that you cannot use smokeless powder in a gun designed for black powder. You will blow it up and yourself along with it.

As for the comparative cleanleness of the two types of powder, black powder leaves MUCH more residue than does smokeless powder. In addition, when the sulfur and potassium nitrate burn they form sulfuric acid and nitric acid which are very corrosive to metal. Black powder residue must be completely removed from your gun as soon as you are through shooting for the day to keep the gun from rusting away. Smokeless powdeer does not have this problem and immediate cleaning is not an issue as long as you don't have any old or foreign cartridges with smokeless powder but a corrosive primer. If you have a cartridge with a corrosive primer, you have to clean immediately.

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[Lee 9]

That is a good article but just for a little more clarification; smokeless generally has a much greater potential energy for the weight and volume, also by adding some other chemical the speed and pressure at which the progressive burn takes place can be controlled the two factors that influence this besides the powder is the ignition and bullet weight.
Blackhorn was engineered to give the same velocity as 777 with around 15 % less pressure. The one thing I do not understand is why the rifle makers have not yet added it to the manuals.

 

[marshall9779]

One thing I don't understand is that if BH209 creates less peak pressure, why do they not recomend up to the 150 gr charge other subs can be loaded to. I wouldn't personally load that much but just curious.

 

[GM54-120]

One thing I don't understand is that if BH209 creates less peak pressure, why do they not recomend up to the 150 gr charge other subs can be loaded to. I wouldn't personally load that much but just curious.

Most 150gr max recommendations are for pelleted powder and not by the powder companies. Even T7 (Hodgdon) does not recommend 150gr of loose or pellet powder. Their loose max is 120gr also.

They dont even recommend 3 pellet charges so BH209 is no different than other powder companies recommendations.

http://www.hodgdon.com/PDF/muzzleloadin ... CKBOX_1=on

Ive shot 120gr and a 385gr bullet in a 6lb rifle. Its no fun and considering the small boost over 110gr, its not worth it in many rifles.

 

[sabotloader]

Lee 9

Blackhorn was engineered to give the same velocity as 777 with around 15 % less pressure. The one thing I do not understand is why the rifle makers have not yet added it to the manuals.

Liability They would be recommending a smokeless powder in their non-smokeless guns. And in todays suit happy world you know what that would lead to..

 

[Lee 9]

Mike, That is a good part of it, if they changed the lawsuit laws so that a person had to prove malice or criminal negligence before the could sue any body it would cut gun repair and doctor bills in half.
There may be some thing else involved also I was talking to a gunsmith on the private forum and he said that there is a letter of agreement going around about not recommending loads that top 22 hundred both for safety reasons and for keeping the lid on so we do not start getting lumped in with regular firearms season and be limited to traditional guns and sights for muzzleloader season. Of course this is a voluntary thing for the betterment of the sport, but if they think it will let them sell more guns they may stick to it.