Powder accuracy?

[BillR1]

So...what causes a particular powder to be more or less accurate with a certain bullet?

I have two powders I'm trying out with my 9mm setup on a 650. The two powers have very similar burn rates and loft/case volume. They produce close to the same speeds and computed power factor with my bullet and crimp settings. One powder however is visibly more accurate with fewer flyers even at the same speed. What causes this? My thinking says the same bullet, OAL, and crimp pushed to the same speed should yield very close to the same accuracy. What am I missing?

TIA!

[DKnoch]

I have not noticed a difference in the few powders I have loaded, but I don’t bench rest my guns much. Is this something you notice shooting from a bench or offhand? I’m curious to hear what the answer may be to the OP though


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[Absocold]

Endless libraries worth of material has been written about the arcane science of ballistics in the quest for accuracy. Long (so very, very long) story short, use the load that works best for your gun.

 

Slightly longer version, for your particular question, the most likely answer is the pressure over time curves are different.

[ARK]

I believe it matters how well the powder measures through your powder measuring device. I have recently shot bunch of loads over chrony and noticed big spread in velocities corresponding to poor accuracy. Shot the same powder after weighting charges on lab scale and accuracy and velocity spreads shrank by half.

Edited February 28, 2020 by ARK