77/22s in .22LR, .22WMR or .22 Hornet are capable of good accuracy, but not always right out of the box.
There are four major areas for improvement:
1) You need to shim the bolt to achieve minimum headspace. Bolt shim kits are cheap and it’s not hard to install them. There are plenty of how to videos out there.
2) The triggers leave something to be desired, not bad, but not what you normally want on a Hornet. Volquartzen, Rifle Basixs and Timney all make trigger kits or replacement triggers for the 77/22.
3) Like the Model 77, Ruger designed the 77/22 receiver to bed in a single horizontal plane with four contact areas (under the barrel block, the tang and the two flats behind the magazine well). They did that to make it easy to get good results with machine inlet stocks. Unfortunately it seems to work better in theory than practice.
Depending on the model some are free floated and some use a pressure bad under the barrel at the end of the fore end. All of them shoot better when free floated. And it’s when you start free floating the barrel that you often discover the action isn’t properly bedded as the barrel keeps sinking as you remove the wood pad in the forend. If you encounter that, just stop and properly bed the action. Leave a business card between barrel and fore end at the front of the fore end and you’ll get adequate clearance ar the bottom of the barrel channel. Also make sure it’s even side to side. You just need to bed the four contact areas discussed above along with 5e first inch or two of the barrel in front of the barrel block.
4) If it still won’t shoot in the 1.25-1.0 MOA range with Hornady 35 gr V-Max (which shoots 1 MOA or better in virtually every Hornet capable of that accuracy), then it needs a new barrel.
Ruger sourced their rifle barrels from Douglas from 1968-1973 and they were excellent barrels and gave the Model 77 a good reputation for accuracy. However in 1973 they switched to barrels from Wilson and accuracy with them was….spotty…. and Ruger rifles developed a reputation for hit and miss accuracy. Ruger stayed with Wilson barrels until 1990.
The 77/22 was introduced in 1983 and from 1983-1990 those Wilson barrels were used, and you can get one that just won’t shoot.
In 1990, Ruger started hammer forging their own barrels and very quickly started producing excellent barrels. If you have a 77/22 made after 1990 the barrel should be fine.