[dannyabear]

Because of the long chamber in my 45/410 single shot pistol, accuracy is very poor with regulat 45 colt loads. I have read about using 444 marlin cases to load brass 410 loads and was wondering about using them to load 45 lc, thinking that would start the bullet a lot closer to the rifling.
Since the case capacity is a lot more than the 45lc case how much more powder should I try to achive a near factory 45 lc load?

[suemarkp]

You can't do it -- the case mouth will be too fat. Loading a .429" bullet would work, but that isn't going to engage the rifling at all. All I can suggest is to use lead bullets of the largest diameter you can find (.454, .455). You can't expect benchrest accuracy with this gun -- it is not intended for that and the sights aren't precise enough nor adjustable.