I've never tried it in .45 Colt, but if your primary objective is least recoil at a fixed velocity of 800 fps or so, then you want to start with the lightest bullet and fastest powder for that big case. The most common light jacketed bullet will probably be 185 grain SWC target bullets for the .45 ACP. Tightwad would be the fastest powder you listed. I don't know your barrel length, but try about 5.0 grains to start. If you have a chronometer you can adjust it.
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