Open up the throats of the New Ruger Blackhawk and Bisley .45 Colt revolvers. They have tight chambers to prevent the brass from stretching now. But the throats are cut to .451 and too tight for optimal Linebaugh loads. Open them up to .453 and you are good to go. Yes I know. This is a little thing, but if you wish to get all you wish from the .45 Colt in a New Model Blackhwak or Bisley model, the Linebaugh suggestion rings true. Follow the link to the article and read Linebaugh's observations yourself.