There is one other load I shoot only in my BlackHawk, not the Old Army w/ R&D Conversion Cylinder. It is 18.8gr of 2400, WLP primer, with a 300gr Sierra JSP. While my 255gr LSWC, 8gr. Unique, WLP load has an overall length of 1.60" allowing it to chamber in any of my 45 Colts the Sierra 300gr has an overall length of 1.68" which is too long to chamber in my Ruger Old Army R&D Conversion. It should be close to the Corbon +P 300 gr 45 Colt offering as I doubt a dear or such could not tell the differance if shot with either.