Greetings to all,
It's been a while. Can anyone tell me if it's possible or even feasible to convert a model 617 in 22 lr. to shoot both 22lr. and 22 magnum. A friend of mine had told me about an article he saw in gun mag that supposedly featured an article about it but I have been unable to confirm or find it. If this is possible, does anyone know of the gunsmith or company that can do this work.
Thanks in advance.

Shouldn't be that hard if you can find a similar 22 mag cylinder or another 22lr cylinder and ream it to 22 mag. Finding a K frame 22 cylinder might be tough. Some people gasp in horror because the 22 lr is .222 and the mag is .224. No worries the extra .002 disappears when it hits the forcing cone. Common they are hardly high pressure rounds in the first place. Just like guys who shot .454 bullets in model 25s with oversized cylinder throats into a .452 barrel. I read an interesting account of an experiment where a rifle was rechambered so that a considerably larger bullet would chamber and head space correctly although the bore was to small. Some small amount of initially high pressure occurred as the bullet swaged to fit the bore then normal. Failures where wrong cartridge in gun is far more apt to be a result of poor chamber fit and headspace than over sized bullet. I personally am not a 22 mag fan. Not enough of a jump to be worth it IMHO, but people like what they like.

You'll need to find a second cylinder that you can have rebored for the 22 Magnum and then have that cylinder fitted to your revolver. My wild guess is that will cost in the range of 250-350 dollars.

For that cost and the approximate cost of 15 dollars a box for 22 Magnum you will gain perhaps 50-100 fps at the muzzle. Because the 22 Magnum is loaded with a powder optimized for a barrel length in the 20-24 inch range. Out of a handgun with a 4 to 6 inch barrel what will be most apparent is the muzzle flash and louder report.

I fitted a new magnum cylinder to my 17-5 that I purchased new from Numerich a few years ago and it works great. As far as the barrel diameters go I have recovered fired magnum bullets and have noticed that other than the rifling marks there are no marks that would indicate that they were too large for the bore. My revolver is more accurate with the magnum rounds than with the long rifle.

I installed a stainless ejector rod to the magnum cylinder so I could differentiate the two at a glance. Both cylinders use the original yoke.

Simple answer, yes. Just fit a 648 cylinder assy. Yorkie Man has it right.

I have been posting lately about doing exactly that conversion. Be sure to obtain a 22LR cylinder that has a matching extractor star to the one in your M 617. The rechambering of the conversion cylinder is fairly easy to do if your hands are strong, you have a padded vice and a fair amount of mechanical aptitude. PM me if you want a write up on the nuances of doing that rechambering job. I added a 22LR cylinder to my M 48 and was disappointed at the resulting accuracy of the 22LR thru the M48 barrel. The opposite happened with the M 617 and 22 WMR going thru the M 617 barrel. I was actually taken back by the exhibited accuracy. As stated the muzzle flash is extraordinary in low light situations. I just ignore it. I have found the CCI 22 Mag ammo is the most accurate, but not by much. I am looking forward to next summer's prairie dog hunting. I will hunt with the iron sights and not a scope because if I wanted to hunt with 22 Mag and a scope I would just go to a rifle. ............ Big Cholla

+1 A friend has a 617 and a 648. I set them up so the cylinders would interchange. Best shooting 22 mag combination was (clearly) the 617 with the 648 cylinder. FWIW the 617 cylinder in the 648 shot very poorly as (probably) would be expected with the 648s' "bigger" barrel bore.

An alternate take is to pick up a used Ruger Single six , or SS Single 10 two cylinder combo package,
IIRC clean used guns usually sell for around $350 to $450.

Ignoring the fact that this has NOTHING to do with the OPs' question which was about converting a 617, you can get a Ruger Single Six if you want a gun seemingly sized for a typical 5 yr olds' hand size and that (assuming the 22 LR/22 mag convertible) shoots 22 LR poorly.

have converted several 17s. found cylinders on ebay and gunbroocker. they can run to 150.00for the cylinder. just saw one today. Brownell makes a great set of cutters, and throaters. all most all work can be done at kitchen table. just finished installing a 6 inch barrel on my I frame 32 long. next will install a j frame adjustable sight. instant target model. just picked up m48 barrel. also making a 22k hornet on a k frame 8 3/8 barrel.

When they're in stock you can buy a new 648 cyl assy (cylinder and extractor) for ~$128 from Brownells'. Downside to a new assy is it will require ratchet fitting...