That's good shootin, if this little 22lr (wood blue)will shoot 1/2" 5 shot groups at 50yds with good ammo I will be well pleased and not even consider the aftermarket barrel, as I remember the triggers on these things were awful back in the day has Ruger addressed this any in the last 15 years?
VA,
I have found the same things that help accruacy in the Ruger m77 cetnerfires to also help in the rimfires
1)Free float the barrel.
2)At least Skim bed the action.
3)Do a trigger job.
Most Rugers can be tweeked to average about dime sizes(5/8") groups with good ammo at 50 yards.I have found them to shoot about like the Marlin 22lr bolt guns. On average. I do not believe the Ruger 22LR rifles to be quite as accurate as the CZ m452s.
Getting them down under 1/2" is tricky in my experience. Unless you want match grade accuracy, I don;t think you will need to go to a Green Mountain barrel if you set the rifle u to give the tube a chance..
Good luck and keep us all posted.