I own a few 22mags. I've got a Magnum Research that is a Ruger 1022M copy with a carbon fiber barrel that is a great gun, light, short, comfortable and reliable. Not as accurate as I was hoping for though, 1 1/4" to 1 1/2" groups at 100 yards. Also own a Remington semiauto that I wouldn't recommend, accurate but unreliable, it jams regularly, which is an issue with a lot of 22mag semiautos, so do your research before buying a semi. I have an old Winchester pump that I really like, I've got fiber optic sights on it and it shoots good with them. I also have a Rossi Circuit Judge which is a revolver rifle with a nine shot cylinder. It comes with a 22lr and 22mag cylinder and you can switch out to whichever you want. I made this gun into a takedown with almost no effort (only one bolt holds the buttstock on) and it is my hound hunting rifle that resides in my backpack all winter. Also own a couple of pistols with switchable cylinders, a Ruger Single Six and a Hi Standard. Warning, 22mag is Loud in a pistol. Had a Marlin bolt rifle in 22 mag that I got as a graduation present, but it got stolen a year or so after I got it.

If he likes lever guns keep your eye open for the Ruger, if you come across one for anything close to a decent price snap it up, I've wanted one for a long time but they are rarer than hens teeth for sale for a reasonable price.

If buying NEW, try and look at the Savage A-17 in .22Mag., Semi-auto, 10 rounds and scope mounts.

I have the .17 w/medium mounts on a 2x7 scope. I love it. Looking at $400 plus.

I have a ruger American, haven't shot it a whole lot but it is very accurate right out of the box

I can't say for the Ruger american 22mag I would expect they are nearly identical.
the 22lr we got 8 of them new the bolts were all a little gritty right out of the box , I rubbed down the bolts with grease then cycled them about 50-100 times each and they smoothed out , wipe the grease off and shoot them and they get quite smooth. that was about 2016 and they are very smooth now

Remington 597 22wmr semi-automatic.
Leupold gold ring 3-9 scope.
Extremely accurate and very fun to shoot!

Another gun that is just right for .22wmr is the Ruger Single Six.

Long ago I had a Marlin 22wmr. Cannot remember why I foolishly sold it.

I have 3 different 22 mags. Savage, marlin, and cz.
All of them are great rifles but you always have that favorite that you feel comfortable with. For me it's the cz. Killed more stuff than smallpox, never had to re zero the scope. Been abused for years and still spot on.

I have 2 both lever guns a winchester and a henry. Hard to tell them apart, bpth nice gums..

I have an older Marlin 25MN and a magnum research semi. The magnum research will clover leaf the 30gr hornady v-max at 100 yards. The marlin shoots pretty good too. I hear the savages are also good

I wish I still had the Winchester model 61 .22 Mag and the Winchester model 94 .22 Mag but sold them along with my collection. Oh, I also Had a Savage over and under in 20 gauge over .22 Mag. I still Have the Marlin Model 882 and the Ruger 10/.22 Magnums, however. Sorry, but any of these would be hard to find nowadays but Henry makes one in a lever, I believe that might be something your dad would like. Others have mentioned some good choices also. Good luck in your search.

Been shooting a Marlin 25 mn mag for over 30 years....but if I had to go out and buy one today...it’d be Henry.

For the record, if you can find a Ruger 10/22 mag for under $650, you should try like crazy to scrape the nickels together to buy it! I have one and the last time I had it appraised it was in the $900 range, and that was a couple of years ago.

I have a Mannlicher stocked CZ in 22 magnum that I am fond of it has a 2x7 variable scope.
Lately I have been fighting off the temptation for a Henry pump 22 magnum.