HOW TO GET A USED CYLINDER OF PROPER SIZE:
You can purchase a used magnum cylinder usually around $75 more or less, on the forums, ebay, Gunbroker, etc. Old Model and New Model cyls will interchange, so that's not an issue. Price range for .22 LR cyl is $65 to $100 depending on condition and seller.
In 30 years I have never installed a cylinder or heard of one that did not function and "time" correctly. They are assembly line produced to a common plus or minus tolerance. The exception and only important issue is that it has enough overall length for your frame at the front hub which is fit and sized to each individual frame window. If too long you can dress it down and is simple to 'fit' with a little stoning, usually under .005", that's not a lot. To have a gunsmith do it would be a minimal charge if you're more comfortable doing it that way.
Cylinders will more likely swap with similar vintage parts.
You should take an overall length measurement of your cyl with a dial caliper in .001 of an inch and seek one the same length or longer (1st photo). The last ten thousandths of an inch is what tells us if it will fit right in another gun or not. Over size can be fitted, undersize causes cyl end shake.
Photo courtesy of "rugerguy"
A .22 cyl OAL is in the 1.622" range with slight variation.
If too long for the frame that's a plus; it just needs to be dressed down at the gas ring indicated by the lower arrow in the photo below, with fine file or dressing stone.
If it fits in the frame, check for too much fore and aft end play called "cylinder end shake" in gunsmith terms.
If nice and snug, check for free rotation and check for a .004" to .007" bar/cyl gap. Cycle the action to confirm all chambers lock up at full cock. And you're safe to go.
A cyl with a gap at the gas ring as shown below at the bottom arrow, will rub on the end of the barrel at the top arrow because it will move back and forth in the gun. Generally if overall length is correct, barrel to cyl gap will be within tolerance:
Photo courtesy of "rugerguy"
Note: Magnum 22s are expensive, but the mag cyl will also shoot 22 Winchester Rim Fire ammo which is being produced again, is a bit cheaper, and with similar performance.
Shims: free shipping, http://www.triggershims.com/
Fitting cyl gas ring to frame:
This normally done in a lathe but we don't all have that luxury.
1st check bushing length end to end at 4 places around it to be sure it's square when you start. If not, square up the offending area.
To file bushing, clamp in vise with the end to be fitted pointing up and level using a level. Coat with black magic marker. Use a medium cutting flat file wide enough to cover the end of the bushing. Use in a draw filing position, parallel to the vise and workbench with one hand on each end of file. Push it away and back towards you concentrating on "feeling" the file surface staying flat on the bushing surface as you 'draw file' away from you then back towards you; back and forth. Check the black ink often to observe if it's being removed evenly. Re-coat with ink and keep going. Check bushing length again in 4 places to be sure it's remaining square. Put in cyl and check in gun before you think you've taken off enough, just in case measurements might be a little off. Clean file every few strokes so you don't get any galling or gouging. When done you can smooth up file marks with 600 grit paper wrapped around the flat file using same draw filing technique.
WHICH CYL WILL WORK:
NM 22 LR cylinders are not all the same. Early NM cylinders are the same as OM cyls.
You need to date your gun or provide a serial # and we can identify when it was made and which cyl would have been provided with it.
Old Model and early NM 22 LR Cylinders have the firing pin groove.
Post c. 1975-1976 New model 22 LR cylinders have no firing pin groove. Either is correct for NMs depending on the vintage.
Old Model and early New Model Cylinders until ~1976 are the same, both fluted and smooth on the rear face. 22 LR chambers are bored straight thru, magnum chambers have a step in the chamber for the case mouth like all center fire calibers.
Post c. 1975-1976 New model 22 LR cylinders look like the one on the right, no firing pin groove, BUT do not have shoulders in the chambers.
.22 Mag cylinders can be fluted (Old and early New Models) or non-fluted and marked .22 Mag (New Models only). They always have shoulders in the chambers.
All of the Old Model Super Single-Sixes had fluted 22 and 22 Mag cylinders. The non-fluted Mag cylinders started for the New Models in 1975 for the Blue guns and in 1976-1977 for the Stainless Steel guns. The elimination of the firing pin groove in the 22 LR cylinder roughly coincides with the introduction of the non fluted Mag cylinders but there are transition guns with both old model cylinders or an old type LR cyl. with the new non-fluted type Mag cylinder. The blue guns switched to the new type cylinders around 64-15000 to 64-17xxx c. 1975 or so before the 1976 Liberty marking and the stainless guns switched about 64-70000 c.1977, after the Liberty marked guns.
The purpose of the groove for the firing pin:
Because the hammer on OMs must be manipulated for loading and unloading. When the hammer is lowered from half cock w/o cocking all the way back to complete the cylinder cycle, the firing pin would contact the cylinder face between chambers and wear on the firing tip as it rubs along the cylinder when manually indexed. (Another reason for drag marks between the notches as well.) W/o the firing pin groove you would also see some dimples in the cylinder face from the firing pin when a cylinder is out of time or from sloppy handling of the hammer. Some gun store clerks are famous for this as well as inexperienced SA users.
This is often seen on the OM Mag cylinders and Smith revolvers because they don't have the groove.
So why doesn't the OM Mag cylinder have the groove?
When the .22 Mag came out, experiments with the same type cylinders with the groove at the rear found that the cartridge would do a lot of spitting and case rupture, so they had to enclose the case head on the .22 Mag. cylinders
No groove on NM cylinders:
Ruger originally put a firing pin groove in the rear of the cylinder to keep the firing pin from battering the cylinder, or breaking.
Turned out, their fear of firing pin breakage was not warranted, because I've never heard of one breaking. And since c. 1975-1976 none of Ruger's .22 cylinders have the groove at the rear. Besides the extra cutting of the groove isn't needed on new models since opening the loading gate locks the hammer. Plus the transfer bar disallows hammer-to-firing pin contact unless the trigger is held back, which eliminates the firing pin from contacting the cyl face when the cyl is not locked in battery. It can still happen but much harder to do.
