It's been my experience that a .22 LR-chambered rifle that shoots MOA (1/2" or smaller) groups at 50 yards is a VERY accurate .22. Most decent .22 rifles will shoot 2 MOA or better at that distance (1" groups or smaller).
A .22 WMR that shoots 1" groups at 50 yards with good ammo (something with the Sierra PSP, for instance) is what I would consider a so-so rifle. The .22 WMR is a more accurate cartridge, with good bullets, than the .22 LR, and so is either of the .17s. A good WMR should be able to approach 1 MOA at 100 yards on a calm day, and a great WMR will shoot MOA or less.
Again, I'll take 1" groups at 50 yards if it means my rifle will easily digest shorts, longs, long rifles, CB caps, etc., and realize that versatility and reliability have a price.
Also, pistols (rifles with barrels with integral chambers) are inherently more accurate than revolvers. There's no cylinder gap to jump, no chamber to get misaligned with the barrel, etc. I would hope that a decent pistol is more accurate than a decent revolver.
Ruger's quality control is slipping. I don't know if this is caused by a complacency at the company or if it is a result of a misguided attempt to cut the bottom line and increase profits. I do know that if they don't make a serious effort to ensure high quality they are in trouble, because the other gun companies aren't sitting around.