Powder measure equation

[Canute Rex]

I was just reading the post about historical use of powder measures and thought of some numbers I came up with from measuring the dimensions of modern adjustable powder measures. These are not guaranteed to be perfect, but they will get you close. After all, it's not so important whether the charge you are pouring is 80 grains or 83 grains as long as it's the same each time.

If you are using a 5/16" drill for your measure, divide the grains you want by 18.3 to get the depth of the hole in inches. (a 5/16" hole 1" deep will hold 18.3 grains)

If you are using a 3/8" drill for your measure, divide the grains you want by 26.4 to get the depth of the hole in inches.

If you are using a 7/16" drill for your measure, divide the grains you want by 35.9 to get the depth of the hole in inches.

If you are using a 1/2" drill for your measure, divide the grains you want by 46.9 to get the depth of the hole in inches.

 

[hawkeye2]

Canute, that's a very handy post, many thanks. It ought to be made a sticky.

 

[Grenadier1758]

One of the first formulas I heard about was that if you were using a 29/64" drill each 1/4" of depth would result in a volume of 10 grains of black powder. A 29/64" hole drilled 1" deep will hold 40 grains of black powder. So divide the grains that you want by 40 to get the desired depth.

We could consider the point of the drill bit as the cone shaped cavity holds a few less bits of black powder, but for all practical purposes the difference isn't significant.

 

[MSW]

cool!

thanks for the post :thumbsup: :hatsoff:

 

[Rifleman1776]

I just use a drill bit the same size as the interior of the measure. I set the measure to the quantity I want and measure the depth then put a piece of tape on the drill bit as my stop point. I usually make a little over-deep. The top can be cut or ground off if needed, or a small hunk of beeswax can be shoved to the bottom to reduce the capacity.

 

[necchi]

That's kind of what I do too, but with the ones I've made of Cedar and Horn pieces I find it inconvenient to have just a hole in the middle.
I like to make them so they have a "pour" section, know what I mean(?) I make one side that has the hole whittled/filed close to the edge, with the top of the hole kind of opened up and tapered towards that side.
I always punch the hole short, open the top the way I want and then re-drill for depth and desired volume.
Using pi`x radius squared x depth never really occurred to me for something as simple as a handy to use powder measure. :idunno:

 

[Rifleman1776]

I like to make them so they have a "pour" section, know what I mean(?) I make one side that has the hole whittled/filed close to the edge, with the top of the hole kind of opened up and tapered towards that side.

Yep, I should have been clearer. My method only works well with wood turned measures. Antlers are the shape they are and I work with wat the ded buck gave me. And those usually do have a "pour" feature.

 

[Canute Rex]

Grenadier, your formula is close to mine. Another fraction of an inch in diameter over 7/16" and it's 40 grains/inch instead of 36 grains/inch.

For those of you who do the tapered antler measures, here's a calculator to give you the volume of a frustrum, a cone with the tip cut off. http://www.aqua-calc.com/calculate/volume-truncated-cone

There are (roughly) 235 grains to the cubic inch.

 

[dwr]

OK....I can count to twenty if I have my mittens and socks off...after that, you guys are leaving me! :idunno: