This R&D conversion is for the Ruger Old Army. The RDROASC converts your Ruger Old Army Stainless Steel revolver to fire the venerable .45 Colt or .45 Schofield Cowboy cartridges! The cylinder was engineered to have a six shot capacity, and to be able to use it in CAS competition. The RDROASC was examined and approved for SASS use by the Territorial Governors. The RDROASC is to be used with either smokeless Cowboy loads or Black Powder 45 Colt/Schofield ammunition. Please see our large selection of cowboy ammunition. (If, after installation, you are unsure of the fit, please take your revolver to a competent gunsmith or contact R & D Gun Shop to make sure you have the cylinder installed correctly.)