I'm not a wheel gun guy, can't offer much help. Hunted with a Redhawk & a 29 years ago. They were finicky. 2"-5" with factory ammo at 50 yds sounds about right from what I've seen from most revolvers.

Try: make sure your scope rings/base are right, try another scope, trigger job, clean bore regularly and when switching bullets, machine rest, try several loads, check cylinder alignment, fire groups from one chamber at a time and compare, lots of dryfire practice to defeat flinch.