I also have a 6" SS GP-100. I mounted a 2-6 power Simmons scope on it for longer distance target shooting. Rested at 25 yards I can consistently hold 6 shot groups around three quarters of an inch, under 2" groups at 50 yards. I am now working on my 100 yard shots on an 8 inch AR500 steel target.
The trigger on mine is fantastic, both single and double action. It is very accurate using everything from 2.7 grains of Bullseye with 148 grain wadcutters to 16.3 grains of 2400 behind 125 grain SJHP. This is the most fun revolver I've ever fired.