Post by whiteleather on Aug 11, 2019 8:49:56 GMT -5
Made up a chart of weight and volume measures for black powder. Here's why:
The blackpowder load for .43 Spanish is 78 "grains" of FFG. Well 78 grains of FFG as measured on my scale will fill the case to the top and beyond. Very dangerous situation.
Turns out the 'grains' are 'grains by volume'. That is a nonsense number. Its like a cop ticketing you for going 10 shoe-lengths per dollar over the speed limit.
True we have volume measured by ounces and weight measured by ounces, but they are not inter changeable. A cup of molten lead (8 fluid ounces) does not weigh 1/2 lb (8 ounces by weight). Likewise 78grains by volume is not the same as 78grains by weight. When working with gunpowder that confusion will kill you dead....and likely hurt people to your left and right.
Why measure BP by volume? Obviously it is easier and faster to measure volume versus weight in the field when muzzle loading. Originally, I believe, a shooter would find that load that works best for his gun and bullet, then make a little cup that held that same load when filled to the top. Cups or measures were of copper or tin or bone or wood. Why they called those volume measure units "grains" is a mystery. Maybe it was grains of wheat or rice or corn to fill the same cup. Wood has grain...maybe it was the number of growth rings inside a measure made from wood...makes as much sense as anything else.
Below is my recent comparison of volume to weight of two common types of blackpowder: FFG or 2F, and FFG or 3F. (Note: To make matters more confusing FFG is called "RS" for "Rifle/Shotgun", and FFFG is called "P" for "Pistol" by the folks at Hodgdon for their Pyrodex.)
I used a CVA brass measure with click detents from 60 to 130 in increments of 10 (https://cva.com/product/hunter-powder-measure/). I did three measures of each detent with each powder and weighed them on my calibrated beam scale then averaged the results. The scale registers to 1/10 grains.
As you can see, the "78 grains" by volume loading if misinterpreted for weight would have been equivalent to "110 grains" by volume. That is a huge factor.
I am impressed that the two powders track very closely from one detent to another. The linearity is a pretty impressive for a brass measure where the two parts wiggle easily.
Weirdly the more finely granulated powder (FFFG/3F/P) weighs LESS at each volume than the coarse granulated powder (FFG/2F/RS). I would have bet even money that the smaller grains would have had less air space and filled the measure more efficiently resulting in higher weights....but such was not the case.
And finally: MY volume measure is not YOUR volume measure. In fact I bet that 10 of these CVA volume measures would show various weight equivalents. If someone using a volume measure they made out of deer antler gives you a recipe for your to use in your French copper measure from 1650...ask the deer antler guy to actually weigh his charge.
So...always double check your black powder loads and demand that any recipes state the units of measure explicitly...preferably by weight. I remember a BassPro gun counter guy from a decade ago telling me that my Smith Carbine would need 150grains of powder to push the bullet out the barrel. The cases for that carbine will only hold 40 grains by weight. So by any measure....that guy was an idiot.
The blackpowder load for .43 Spanish is 78 "grains" of FFG. Well 78 grains of FFG as measured on my scale will fill the case to the top and beyond. Very dangerous situation.
Turns out the 'grains' are 'grains by volume'. That is a nonsense number. Its like a cop ticketing you for going 10 shoe-lengths per dollar over the speed limit.
True we have volume measured by ounces and weight measured by ounces, but they are not inter changeable. A cup of molten lead (8 fluid ounces) does not weigh 1/2 lb (8 ounces by weight). Likewise 78grains by volume is not the same as 78grains by weight. When working with gunpowder that confusion will kill you dead....and likely hurt people to your left and right.
Why measure BP by volume? Obviously it is easier and faster to measure volume versus weight in the field when muzzle loading. Originally, I believe, a shooter would find that load that works best for his gun and bullet, then make a little cup that held that same load when filled to the top. Cups or measures were of copper or tin or bone or wood. Why they called those volume measure units "grains" is a mystery. Maybe it was grains of wheat or rice or corn to fill the same cup. Wood has grain...maybe it was the number of growth rings inside a measure made from wood...makes as much sense as anything else.
Below is my recent comparison of volume to weight of two common types of blackpowder: FFG or 2F, and FFG or 3F. (Note: To make matters more confusing FFG is called "RS" for "Rifle/Shotgun", and FFFG is called "P" for "Pistol" by the folks at Hodgdon for their Pyrodex.)
I used a CVA brass measure with click detents from 60 to 130 in increments of 10 (https://cva.com/product/hunter-powder-measure/). I did three measures of each detent with each powder and weighed them on my calibrated beam scale then averaged the results. The scale registers to 1/10 grains.
As you can see, the "78 grains" by volume loading if misinterpreted for weight would have been equivalent to "110 grains" by volume. That is a huge factor.
I am impressed that the two powders track very closely from one detent to another. The linearity is a pretty impressive for a brass measure where the two parts wiggle easily.
Weirdly the more finely granulated powder (FFFG/3F/P) weighs LESS at each volume than the coarse granulated powder (FFG/2F/RS). I would have bet even money that the smaller grains would have had less air space and filled the measure more efficiently resulting in higher weights....but such was not the case.
And finally: MY volume measure is not YOUR volume measure. In fact I bet that 10 of these CVA volume measures would show various weight equivalents. If someone using a volume measure they made out of deer antler gives you a recipe for your to use in your French copper measure from 1650...ask the deer antler guy to actually weigh his charge.
So...always double check your black powder loads and demand that any recipes state the units of measure explicitly...preferably by weight. I remember a BassPro gun counter guy from a decade ago telling me that my Smith Carbine would need 150grains of powder to push the bullet out the barrel. The cases for that carbine will only hold 40 grains by weight. So by any measure....that guy was an idiot.
This is very similar to the cap I use on a GOEX can.