powder charge ranges and their suitableness for a given caliber

[Giant81]

I've been looking at reloading charts and I'm starting to discern some patterns from it. ( or, at the very least I THINK I'm seeing a pattern, maybe I've just been sniffing the Hoppe's for too long.)

What I'm noticing is that it's very obvious that some powders have a very short range between min/max and others have a much larger range. Consider the differences in tightgroup VS BlueDot for example.

Does a larger range between min/max tend to indicate a powder that would be better at giving me consistent velocities for a given caliber?

I know more serious competition shooters are using TG then BD in their 9mm loads so obviously that's not the whole story. Yet, I do tend to wonder why many have found it better to use a powder that 1/10'th of a grain + or - can create a much greater velocity variance than others.

[Hammbone]

Let me say this. I've been reloading for a whopping 6mo now. I'm an Engineer and I analyze EVERYTHING to death. Going into this I thought I was going to take the bull by the horns and really figure this thing out. Make charts, graphs, mathematical modela...etc. What I'm finding is that its much more complicated than I bargained for (mathematically speaking).

But to address your question: I think you'll find that while the absolute difference between start and max of TG and BD are greatly different, there % difference is similar... (i.e., you use more BD than TG, so on a % basis you get a bigger spread for the absolute value). In addition, almost always, you use a much lower charge with faster burning powders - hence, again contributing to the difference your seeing between say TG and BD.

A lot of "action" or "practical" shooters are opting for faster powders because the quick burst imposes less of a felt recoil. There are the gases generated and therefore less muzzle flip, and therefore its easier to get back on target. That being said, my personal experience is that slower burning powders produce more accurate loads.

[Steve RA]

The slower burning powders, which generally use a larger quantity for a given velocity, also generate more gas. This is good for open shooters with comps as more gas makes them more effective.

[jlamphere]

You will get a larger range in the slower burning powders than in the fast powders due to the slower development of pressure. Fast powders spike to max pressure while slow powders have more of a slope in pressure. That is one reason you have less of a chance of blowing somthing up with a BD vs. a TG or N310. Comps do add another factor into the mix as well.

Edited February 5, 2013 by jlamphere

[Giant81]

I think the proportionality of the variance is probably about right.

I've chosen Unique to start with and ended up finding a bottle of blue dot in my parents closet (which is funny since they've never reloaded anything ever). So I have a pound of each.

I think I'll stick to slower powders because of their larger range for learning then bump of to a faster powder only if I'm finding some property of the slower ones that I'm not happy with.

I just figured since I'm using a rotary powder drop (hornady lnl ap), and there is always some amount of variance in the drops, that using a powder with less sensitivity to variance (slower powders that have a larger range) I'd get a more consistent round. Which in the end would turn into better accuracy.

I hadn't thought of the pressure curve and how it effected recoil.

Thanks for the help.