Some neighbours are new hunters. They are getting discouraged at not seeing any bucks where they are hunting and have decided that getting the odd grouse or too would boost their success rate. They are thinking of getting some kind of grouse gun.
I don't know what to suggest. I have a couple of very old .22 rifles myself, a 410 and a 20 gauge and wouldn't know what to recommend in an off-the-shelf new .22.
I know the Ruger 10/22 is popular, but maybe that is because of all the "cool" accessories you can get for it and the fact that it is semi-auto. I would be inclined to recommend a removeable magazine bolt-action myself, most likely with a good scope.
Where I used to hunt grouse (Ontario) you'd be at a severe disadvantage bringing a .22. There have been times I could have used one (close/stunned birds) but mostly it's a shotgun thing. The season I shot the most, it was with a 20ga Wingmaster, 21" CYL bore barrel. Never had more than 3 pellets in the breast and believe me, I wasn't going for head shots. Aim/pull the trigger. Some birds had no pellets in the breast. Either way, when you clean grouse..it's easy to find the pellets in the breast. Anyhow, that had less to do with the gun=just a good year for birds. Felt like the gun was bringing me luck though. lol
For a 22-it depends largely on the budget. I'd always suggest a scoped bolt-action for the reasons noted in earlier posts, but WHAT 22 is the bigger question...and scope/no scope? Budget? young/strong shooter or younger/slight build? Not many inexpensive .22s I've held recently had decent iron sights. I've seen similar ones on $90 pellet guns.
There is a CZ452 Scout in the EE right now, allot can be said about the convenient size, accuracy etc. of a gun like that, etc. Sights are OK, but with a half-decent scope...no grouse should be safe inside of 50 yards, and shooters of any size could probably manage that thing. Granted, one person's idea of a "half decent" scope...
The 22 I shoot most is a 20" Tikka T1x, I use it more than my CZs now. They make a 16" barrelled version of that gun too, could be a stellar choice.
If economy is paramount, a used Savage or Marlin might be where to look. Shotguns-due to the scarcity/cost of .410 ammo...and..the fact that I can't seem to hit anything moving with .410

...I'd suggest a 20ga pump. We have an 870 Youth 20ga that sees allot of use, but if shopping new/used...I'd probably be looking at a Mossberg 500.
Was feeling nostalgic...so I dug-up a photo