Rugers can be problematic as they come from the factory, but a few simple steps can turn them into pretty nice-shooting rifles.
The first thing to check is whether the firing pin strikes are deep and that there are no misfires with various kinds of ammo. If strikes are shallow and wide, the firing pin tip can be ground narrower, but with rounded edges to improve ignition.
Despite various attempts to free-float 10-22 barrels, they seem to shoot best with a pressure point near the end of the forend that provides about 5-8 pounds of vertical pressure. That's because there's only one stock screw and it's important to add pressure to the barrel to keep the receiver down in the stock, especially when a scope is used.
After loosening the stock screw, if the receiver fits loosely in the stock, there are two ways to make it better. I prefer to glassbed the receiver and the rear of the trigger mechanism; however, have used a few layers of electrical tape on a buddy's rifle receiver sides to tighten things up temporarily and we were astounded at the accuracy improvement. He went on to win a plinker class IR50-50 match that day!!!
The Ruger sporter barrels are fine for plinking, but if you get serious, a new barrel is necessary. I've had great luck with Green Mountain barrels, but most of the after-market bull barrels made are very accurate.
You can find out other low-cost tips to improve your rifle at rimfirecentral.com Tips and Tricks Forum.