In reloading for the Ruger Blackhawk Convertibles (.357/9mm & .45 Colt/.45 ACP) the most notable problem is that the chambers are sensitive to bullets with a long bearing surface. By that, I mean most bullets with a bearing surface that extends beyond the case mouth will give chambering problems. I've had my best luck using 125 grain TCL and 200 grain SWC bullets seated with the shoulder flush with the case mouth.
Since you are getting good accuracy already, and since your loads are only intended for plinking, why experiment with different bullets at all? I would be perfectly happy using your 115 grain bullets knowing that they work well in your Blackhawk and semiauto pistols.