Basics of powder burn rates and useage

[Jim Watson]

The OP mentions common pistol calibers, including 9mm.

Once upon a time, Accurate Arms had a footnote for the caliber stating that fast burning AA #2 might not function some European pistols with less than full charges.

The NRA reported that the then-new H&K P7 with gas retardation was not reliable with reloads of fast burning Bullseye powder. Unique worked fine.

C.E. Harris recommended selecting a powder showing a charge in the range of 5 to 7 grains for 9mm; paralleling the medium burn rate powder used in European ammo.

So "burn rate" does matter.

 

[hdwhit]

locknloader wrote:
...good information about how burn rate comes into play when selecting a powder for a given round.

There are, as you noted, some general guidelines, like: "From among the powders listed in the manual, try a "faster" powder if you have a shorter barrel."

Beyond that you are not likely to come across any "good information" outside of the powder company's laboratory. The simple reason for this is that there is no industry-standard protocol for determining a powder's burn rate, so what one tester determines to be the fastest powder out there may be 5th on the list when someone else tests it. Compare the burn rates shown on the Hodgdon site with those published by Vhita Vuori.

 

[74A95]

The OP mentions common pistol calibers, including 9mm.

Once upon a time, Accurate Arms had a footnote for the caliber stating that fast burning AA #2 might not function some European pistols with less than full charges.

The NRA reported that the then-new H&K P7 with gas retardation was not reliable with reloads of fast burning Bullseye powder. Unique worked fine.

C.E. Harris recommended selecting a powder showing a charge in the range of 5 to 7 grains for 9mm; paralleling the medium burn rate powder used in European ammo.

So "burn rate" does matter.

It matters with respect to how strong the recoil impulse is. Fast powders might generate less velocity than slower powders. And slower powders require more weight to produce the same speed as faster powders, and more powder weight produces more gas which produces a stronger recoil impulse, even when pushing the same bullet to the same speed. So, yes, burn rate matters with respect to the recoil impulse, but it is tied to gunpowder weight via the conservation of mass principle as part of the weight of the ejected mass which affects the strength of the recoil force. That is described here, for folks who might be interested: https://en.wikipedia.org/wiki/Recoil

 

[Reloadron]

Jim Watson:

The OP mentions common pistol calibers, including 9mm.

Once upon a time, Accurate Arms had a footnote for the caliber stating that fast burning AA #2 might not function some European pistols with less than full charges.

The NRA reported that the then-new H&K P7 with gas retardation was not reliable with reloads of fast burning Bullseye powder. Unique worked fine.

C.E. Harris recommended selecting a powder showing a charge in the range of 5 to 7 grains for 9mm; paralleling the medium burn rate powder used in European ammo.

So "burn rate" does matter.

Pistol aside for a moment, burn rate also matters a whole bunch in rifle especially when we look at gas operated rifles and what the pressure is at the gas port. Not enough pressure and the rifle will short stroke, too much pressure and we can beat the heck out of the gas system parts. Just right and the rifle will cycle as it was designed to do for a specific gas pressure at the gas port.

Gas guns aside Hatcher's Notebook right around page 322 & 323 has some good pressure curve verse velocity for the 30-06 Springfield fited from a 1903 Springfield rifle. Pretty good stuff.

Ron