Originally Posted By AeroE:
The burn rate of your gunpowder choice should be matched to the bullet weight you want to shoot. The way to discover what this means is by sitting down with load tables and paying attention to which gunpowders are used with each range of bullet weights. As you move from light to heavy, you'll notice a shift in the gunpowders listed with each bullet, with considerable overlap across weights.
There is no best gunpowder, everything we have to choose from is great, but there are better choices for one reason or another. Metering through a measure is a pretty good reason, and the ball powders meter best, but the fine extruded powders meter almost as well, so sometimes there is no clear preference.
Sometimes we have to choose a gunpowder because it's available locally. Which brings me to another point. When you start, buy one pound containers until you decide which gunpowder you want to settle on.
I'm a fan of Reloder 15 for bullets ranging from 52 grains weight to 80 grains. This one is a little slow for the 52 grain bullets, but it fills the case and just works great anyway, and still produces over 3200 fps in my 24 inch barreled gun. That's pretty fast.
H335, BL-C(2), W748, andTAC are all ball powders that will work for you. Reloder 15, H4895, IMR 4895, and Varget are extruded powders that work. There are probably another 8 that I could name.
What that all means is that you won't screw up by simply picking one. You might find out later you like something else better, but it will be for relatively minor reasons.
How much R15 are you using under the lighter bullets? Alliant publishes no load data for bullets lass than 62 grains that I could find. While that certainly doesnt exclude its use in lighter bullets did you just take the 62 grain load and add 10% to it for a 55?