Difference between slow burning and fast burning powder

[blacklab2011]

Looking at reloading 9mm & 40sw. Curious what the difference between a slow and fast burning powder. What application is best for each?

Thanks!

[jmorris]

A fast powder with a heavy bullet more often than not feels like there is less recoil than slow powders. Ported guns are the exception to the rule as the extra gas provided by the slower burning powders exiting provides the force to keep the pistol from moving as much.

[redbird1976]

Looking at reloading 9mm & 40sw. Curious what the difference between a slow and fast burning powder. What application is best for each?

Thanks!

In general terms a faster powder reaches the peak of its pressure curve faster than a slower powder powder. You should get a more complete burn in a shorter barrel using a faster powder. I've seen something that Rob Leatham wrote on the effects of the burn rate and how it affects the recoil impulse on the site somewhere. Do a search and see what you come up with.

I used fast powders for many years. In the last couple of years, I've switched to a slower powder to lower the pressure in my major loads. The only perceived draw back I find using the slower powders is that it takes a little more than the faster powders I was using. As a result, my loads are typically a little hotter than what most people shoot. I've also found that the slower powder is useful in magnum loads for my hunting guns. Slower powders also produce more gas to work with compensators on open guns.

It takes less powder to make major with the faster powders, but the trade off is that you'll be loading at or very near SAAMI max pressure for the either cartridge. I was getting burst primers with my load using a fast powder, and that was loading below the max load to the specified OAL. It may have been a bad lot of powder, but I was loading from the same jug of powder and sleeve of primers. I switched powders and the burst primers went away. Fast powders make for some good minor loads. I have a 147 grn GSSF load that feels like shooting .38 wadcutters for PPC.

Hodgdon has a powder burn rate chart on their website that compares the burn rates of most the current manufacturers powders.