Sciencemadness Discussion Board

"Grain Propellant" aka "Cowboy Powder"

ShotBored - 1-2-2022 at 06:53

Hey all, long time no talk. I'm in the middle of switching into a new career field in energetics so that has eaten up a lot of my time. The other day I came across an old formulation in one of our retired formulations books at work for a material referenced as either "Grain Propellant" or "Cowboy Powder", both of which are seemingly useless colloquial terms imo. I can't find any real mention of either in literature.

The formulation seems extremely odd to me and I'm trying to understand what this material would have been used for? If anyone is familiar I'd appreciate an explanation:

91% 4FG Black Powder
9% Calcium Carbonate

The material has a super super old GOEX label on it but I can't find any reference to the Part Number anywhere. Has anyone heard of this material? Why would you ruin perfectly good Black Powder with Calcium Carbonate, particularly with respect to the moisture issues already present in BP...then you add hygroscopic CaCO3?

ShotBored - 1-2-2022 at 07:31

I realize that the CaCO3 may function as a coolant, however I would think even in older times that there were better options for coolants, such as NaHCO3, MgCO3, etc.

SWIM - 1-2-2022 at 17:00

If this stuff really has an old-West origin, then the choice of CaCO3 may just be a matter of availability.
Lime you could find pretty much anywhere in the 19th century.

Magnesium carbonate you'd have to buy special for the purpose.

Baking soda (Saleratus in the south back then) was more common, but costlier too. Lime was mighty cheap.

Also, Lime was probably easier to find in less civilized areas where less baking was done.
Those frontier towns that were 95% male and everybody seemed to pretty much live on cured pork, corn dodgers, whiskey and smoked oysters.

As for its purpose, 4FG is, if I'm not mistaken, some fast powder.
Maybe this was just a way to slow it down enough to use in weapons requiring something slower like a large caliber rifle.
Better to just have the right grain size, but maybe at least this could be used if FFFFG was all you had available and you wanted to shoot your 45/70 at some buffalo.

I tried looking this mixture up, but as you probably already know "cowboy powder" and "grain propellant" are search terms that give very unsatisfying results.

ShotBored - 2-2-2022 at 07:00


Knowing the place I work at and my predecessors, that is actually not as farfetched an explanation as it might seem at first glance. The history of my facility is bathed in shortcuts and half-assed fixes, so i actually think your explanation of a cheap workaround is probably the most likely scenario.

Somebody needed a slower burning powder and instead of sourcing the correct replacement, they just decided to add whatever they had laying around to the formula to slow it down, damned be the future consequences.

unionised - 2-2-2022 at 08:37

Quote: Originally posted by ShotBored  

then you add hygroscopic CaCO3?

Limestone is not very hygroscopic.

ShotBored - 2-2-2022 at 09:55

Yes you are correct there, definitely an error on my part to mention that CaCO3 is inately hygroscopic. However I was under the impression that the hygroscopicity of carbonates can be increased due to aging as well as initial manufacturing conditions and that after a long period of time they can absorb a noticeable amount of moisture from the air:

Guo et al

The particular section i'm looking at mentions: "Our work
also observed that significant hygroscopic growth of aerosol
particles, such as Ca(NO3)2 and CaCl2, occurred at RHs as
low as 10 %. This implies that aged carbonate particles can
take up a significant amount of water even under very low
RH, leading to changes in their diameters and morphology
and thus impacting their optical properties and direct radiative effects"