Odd question about powder burn rate

[hemiford]

The following thought occurred me. Now, I may be way off base, but here goes:

If you need a powder with even slower burn rate than say H50-BMG,
maybe for some very large capacity case, could you not mix into the
powder load a SMALL amount of powdered drywall, or chalk, or something else inert, to slow down the burn rate ? I imagine the chalk would need to be
mixed in very uniformly, perhaps only as a surface coating to the granules.

I've not read about this anywhere.

 

[4bycamper]

OK If I hear you right, You want to load a case like 50 BMG or larger with an experimental load or powder combination that has not been proofed by someone who does this sort of thing. Seems extremely risky.

When I load, I use published load data. Then I find the load the rifle likes best.
When the rifle prints sub moa at 200 yards, I'll take it over to the High Power range and stretch its legs a bit. Never needed to modify a powder.

So you want to put 110+ grains of a modified powder into a really large piece of brass,
load a 300+ grain bullet, and squeeze the trigger?

If you survive, please let us know how this turned out.

 

[Mikecr]

There 'think' there are surplus powders that are slower than H50.
Welcome to Bartlett Reloaders - Jeff Bartlett

 

[dkhunt14]

Hodgdon US*869 and Vihta Vuori 20N29 are both slower then 50 BMG. Matt

 

[azsugarbear]

Interesting responses......but the original question still needs to answered. I personally do not have enough knowledge to comment, but I did hear a guy once at a seminar who explained that chemicals were added to flake or ball powder to ****** ignition much like coatings added to breakfast cereal to keep the flakes crunchy longer. I'm not at all sure if chalk would be the choice for that. Hopefully someone who works for one of the powder companies will see this one and chime in.

 

[Engineering101]

Actually data from QuickLoad shows burn rates of powders as listed below. The smaller the number the slower the powder.

US869 - 0.2735
H50BMG - 0.2705
RL-33 - 0.2700
20N29 - 0.2400

 

[Engineering101]

I probably should have mentioned in keeping with the original question that the slowest powder listed in QuickLoad is RL-50 which is rated at 0.2170.

 

[Lefty7mmstw]

The following thought occurred me. Now, I may be way off base, but here goes:

If you need a powder with even slower burn rate than say H50-BMG,
maybe for some very large capacity case, could you not mix into the
powder load a SMALL amount of powdered drywall, or chalk, or something else inert, to slow down the burn rate ? I imagine the chalk would need to be
mixed in very uniformly, perhaps only as a surface coating to the granules.

I've not read about this anywhere.

you would have to be careful about how gritty the substance is; I could see chalk washing out a bore rather quickly considering how hard it is on your hands.
I'd stick to available powders (even mil surp. powders usually have a canister powder sibling of similar burn rate to start with) unless you have pressure testing equipment or a rifle you don't care much about and a very long string.

 

[dkhunt14]

You would have to be careful because adding anything to powder would effect the load density and the way it burned. I know guys that put fillers in powder to get a fuller case and the stuff must have balled up and caused a pressure spike. It blew up a couple of guns. My reloading powder charts show US 869 slower then 50 BMG. I know it gives more velocity then 50 BMG in a 50 cal so I believe it is slower. Reloader 33 should be faster then 50 BMP but is made with the new technology to make the powder burn more throughout the barrel like Reloader 17. It gives a different pressure spike. Matt

 

[tim_w]

The only way I have ever messed with a powders burn rate was granule size separation of ball powder with lab mesh sieves of different sizes.

 

[tim_w]

double