Last week with a customized Glock 20SF, (standard length KKM Barrel, Trijicon RMR, trigger job), we were banging steel at 130 yards every time... even head shots were not a problem. So we stretched it out to 180 yards and with an 11 O'clock hold... the steel would ring no problem... The RMR makes all the difference when reaching out there...
Impressive, sounds like a lotta fun too. Did you have the slide milled or using a dovetail mount?