Thanks for the information uscra112 and Wayne. I had my doubts about single powder crossing from pistol to 303 British. I just downloaded the Lee dipper chart of grains for several brands of powder. Thinking that by looking up load data I can find something that will have a dipper that if not at starting load is not too much over. Good to have more than one manual or reputable source to confirm I'm in the safe range. That is what I did (with some help) for 38 special, the Lee loader scoop did not yield an exact starting load with unique but was close to the middle between starting and max load for 125 gr cast bullet.
Will look into Red Dot and see how that would work. Sort of complicated to work out because what mold(s) I get to cast boolits with will impact what powders I can use and hit a good load using a Lee dipper. I know a powder measure would be useful but would like to work out how to do this on a budget, would rather get a scale than measure if I was spending money.
Noticed in the Lee manual all the 303 British load data was for jacketed, not sure what difference jacket vs lead makes but will certainly need to figure that out from some other source.
Still waiting to get out and try that first batch, been too darn cold.