[Nick_C_S]

Propellant burn rates are about as clear as mud. Variables abound.

I've looked at a lot of charts. And one over-arching concern I've had is with the "perceived linearity" of charts that simply number the powders from 1 to Whatever. I think they lend themselves to painting an inaccurate picture.

Hodgdon's burn rate chart is a popular example. And in the case of Hodgdon specifically, they position some powders that just leave me shaking my head.

For example, they have AA#5 at position 41, slower than Power Pistol (pos 34). It's been my experience that AA5 is pretty fast for an intermediate speed powder - very close to Unique (pos 31). I find Power Pistol to be about the same burn rate as HS-6 (pos 42), albiet, more energetic (per reynolds357 & 44 AMP's post).

Hodgdon has HP38/W231 (pos 28, 29) slower than AA#2 (pos 26) - it's not. AA#2 is actually pretty slow for a fast burner. And I find TiteGroup (pos 15) to be virtually the same speed as AA#2; and Hodgdon has TG sitting very close to the very speedy Bullseye (pos 13). That's a serious head-shaker for me.

I like the Accurate Arms/Ramshot chart. First, because it is non-linear, so it doesn't imply something that isn't true. It has rows that show powders at (or very near) the same burn rate; and this makes much more sense to me. Secondly, it has the propellant's burn rates correctly positioned based on my personal experience. It shows Bullseye a tick faster than HP-38/W231; and HP-38/W231 a tick faster than AA#2, TiteGroup, & Red Dot; and AA#5 a tick faster than Unique; and Unique a tick faster than Power Pistol and HS-6. These all fit in perfectly with my personal experience.

All said, I think it's important to contemplate burn rates in the context of the full picture of loading. All told, even if the perfect burn rate chart existed, it's only a guideline to point you in the right basic direction to fulfill a loading purpose. It is just a basic step early in the process of creating ammunition specific and correct for a purpose. Context and perspective.