There is no “best” powder as it depends on your bullet load combination and what your gun likes.
Get yourself a burn rate chart, it will list all the more appropriate powders for the.45ACP
Generally fast to medium fast powders work the best.
The first 30 to 40 powders on the list fit in this category.
In order of approximate burn rate (depending on whose chart you reference)
These powders I have used and have performed well for me in standard pressure loadings.
There are others but any of the following will serve you well.
All of the best powders for .45 ACP in a 1911 are probably fast enough burning that it won't make much difference but the old rule was to use faster powders with shorter barrels. Win 231 or Bullseye will get the job done.
The powders that I have used to load .45 are, in chronological order:
Zip (and then back to Clays)
If I had to pick one, based only on its performance, it would be N320. Based on what I need a .45 powder to do, and figuring in cost, Clays is my favorite. That said, Clays is not a versatile powder, which most of the others are.
Most of my choices are in the medium-medium slow range. I've found with the "much faster" powders that max loads spike pressures waaaay to easy. I find those I listed above are much more forgiving and easier to find a "sweet spot" for accuracy/cleanliness/shootability/economy. Tracy
If I had to get by on only two powders, I'd pick W231 and HS6. I'm getting real fond of VV N310 so that would be my third. Heck, let's just list 'em all:
I think that's all the powders I've ever tried in 45 acp except for VV N320, which didn't impress me over W231. I did try some BlueDot for some high capacity loads, and it was dirty and flashy. Should have asked here first, I reckon. I'm going to try some Power Pistol very soon cause it may be a clean alternative to Unique, which doesn't meter all that good.