I’m planning on building a .32-40 200 yard match rifles. I’m limited by rules to using Black Powder (BP) only and I have no problem with that. It seems that the most accurate shooting is with smokeless powder though. And I’ve wondered why that is and I have thought it may be the fact that grain structure is much more uniform in smokeless powder. Burning rate, all other things being equal (which is usually not the case) is determined by the surface area of the individual grains of powder. Because the grain structure of BP varies from case to case and batch to batch, the pressure curve would be different shot to shot and indicated by reduced accuracy. If this is true would sifting powder to produce more uniform grain size per load lead to greater accuracy. What are your thoughts as to why smokeless powder loads are more accurate.
Cheers Richard

So, Randy, what would a bullet look like whose center of mass is congruent with center of form?

Technology may exist for doing that, Randy. I've read of a device called the Juenke Internal Concentricity Comparator which does what you're referencing to with jacketed bullets. Descriptions of how it works and how it's used baffled me a bit (ok, a lot), but the seriously scientific experimenters seemingly worship its attributes.

I know not if it's applicable to cast bullets, but suspect it may. They're rather expensive so I guess I'll never find out for myself.

SchwartzStock wrote on Mar 24^th, 2024 at 11:34am:


Indexing is certainly a step in the right direction, but which of the mould lines do you use? How do you tell them apart?  If you mark the line in any manner, even with an ink marker, you will make the mass even less concentric.

An important thing to realize about F.W. Mann's findings is that even when the bullet is perfect going into the chamber, by the time it comes out of the muzzle it is often buggered up. Indexing bullets does nothing to solve this problem.

Chris.

I can only speak for GOEX BP, I've never used anything else.

I tried sifting and used a fan, at a distance that I thought would be very gentle but, it made a mess, doing just one can. I scared myself when I seen the mess!!!

That was done to remove the "fines" in the #2 powder so, I went to #1 and found much better accuracy in my slug gun and cartridge rifles and near sieved again.

frnkeore wrote on Mar 25^th, 2024 at 12:31pm:


Goex powders generally have a much larger variation in granule size than Swiss.   The only exception might be Goex Fg  which is very coarse.

I know a few people that "sift" Goex powders by going outside on a breezy day and pouring the cans into a large bowl.  The dusty stuff just blows away in the breeze and the coarser stuff lands in the bowl.  I've never tried it.

I think it's certainly worth trying if you can't get Swiss.  I believe that Track the Wolf sells screens of various sizes for this purpose. 

Chris.

I might be a little late on this, butt.....
I always imagined it counter to the goal to buy the best in graded powder, or screen what you have to improve the particle size, weigh and drop it in the case, and then compress the daylights out of it, making a solid plug of the top half, crushing all the uniform grains in the process.