Difference between OM & NM Single six cylinders?

[Rockrat]

Just trying to find out what the difference is between the OM and the NM cylinders, for the Single Six.

Thanks

 

[rugerguy]

for the most part the "old model" 22 cylinder has a firing groove going around the rear, the NM does NOT ( yes, some of the "new model" guns at first came with left over 'old model ; cylinders so try not toconfuse the issue.
later on the gas ring ( stub) in front ,became a bit longer?? I know on the Blackhawks they set back the barrel further into the cylinder frame window, thus the 'stub' is LONGER.......easy to tell when they are sitting side by side........

as for the 22 magnum, the old model ones are NOT marked "magnum" the newer ones are, as well as smooth, no flutes............
hope this helps

 

[Rockrat]

Thats what I needed to know. Guess I have an old model 22 mag cyl

 

[xtratoy]

I asked this question before and this is the answer I received then. "The NM cylinders don't work in OM pistols. Not so much the length, which can be fitted (i.e. sanded to the slightly shorter length), but that the ratchet wheel (term??) is a different size (smaller on NM). OM = .625", NM = .58" IIRC." It seems like someone also showed a picture of the ratchet that appeared to verify the above statement.

 

[Barnhart]

I have what I believe is an old model 22 lr cyl. and a new model s/s with a 22 mag cylinder. The ratchet wheels are different as stated and the base pin in the nm single six is a lager diamater. Hence they won't interchange at all. Someone correct me if I am wrong.

 

[rugerguy]

the cylinder pin is the same diameter for all of them, the front end cap has changed over the year,as well as the grooves, and a shoulder added to some of the models, but the diameter is the same....I seem to recall that when a gun would be sent back to the factory for fitting, they installed a new model cylinder, in old model guns over the years, just "fitted" it to make them work????we've put different ones in other guns over the years and except for the "dropping in" and the length of the gas ring (stud) and the distance the barrels is "set back" into the window, could get them to work..thats why its called 'fitting" as well as timing and alignment...if in doubt have it done by a competant gunsmith or send it back to the factory....many folks are "just lucky" they got them to fit ( or as they often say "drop in....") still things to be "checked".........SAFETY FIRST !!

 

[chet15]

The cylinder opening for Ruger's OM Single-Six and NM Single-Six were the same, so the cylinder lengths for all those cylinders are pretty much the same, but as rugerguy says, some will just drop in and others need a little extra filed off the front cone in order to fit.
Ruger got rid of the firing pin groove in the LR cylinder and began rollmarking an unfluted cylinder for the Mag. in late 1975 for the blue guns. For the stainless, these changes happened in mid-1976.
Chet15

 

[rugerguy]

something "changed", here's what one has to be aware of and watch out for...

 

[flatgate]

Well said, Dan!

One picture is worth a thousand words.

flatgate

 

[Hondo44]

I asked this question before and this is the answer I received then. "The NM cylinders don't work in OM pistols. Not so much the length, which can be fitted (i.e. sanded to the slightly shorter length), but that the ratchet wheel (term??) is a different size (smaller on NM). OM = .625", NM = .58" IIRC." It seems like someone also showed a picture of the ratchet that appeared to verify the above statement.

xtratoy,
Those dimensions are correct; in fact my ratchet diameters vary from .540" all the way to .623". That's on 4 NMs and 5 OMs (actually 13 different cylinders because I measured both cylinders on the 4 NM convertibles. And the small diameter ratchet cylinders will work in any single six once fitted for length however are a little more likely to need the pawl fitted.

The good news is all of the 5 OM larger ratchet cylinders will fit in the 4 NM guns based on measurements (some were too long to actually be placed in the cylinder windows). That's because at least all 4 of my NM guns have a ratchet cut of at least .640".

So the only issue of fitting non-original cylinders is the 2 lengths (OA and cyl + ratchet), not the NM vs. OM issue. However, in my experience, guns closer to the vintage of the gun tend to be closer fits or 'drop ins'. And as Dan so aply illustrated.

 

[Wyandot Jim]

I have an old model Mag cylinder in a new model at this time. Dropped right in and is a good fit.
Jim

 

[rugerguy]

yes, if there was an "issue" with the ratchet, you would know immediately, as the cylinder would NOT engage, index or rotate...it has to "fit" into the window lengthwise, ride on the frame, NO gap, and be close enough to the barrel to have a proper headspace b/c gap about .004-.006" ideal...seen closer and see lots further, just watch for side blow ( splatter)...bottom line is it indexes, LOCKS up ,all 6 (now 10) chambers??and the chamber bore aligns fairly well with the barrels forcing cone....a 'range rod' can be used to check this........

 

[Hondo44]

Here's a confusing situation I just learned about. I found this photo in an old thread showing the difference between OM LR and OM Mag cylinders.
The firing pin groove in the one on the left is a little hard to see but it's evident at the 5:00 o'clock position.

Chet, does the NM LR cylinder w/o that firing pin groove otherwise look the same with the rim around the edge? If so, there must be a later style NM LR cylinder that looks exactly like the old model Magnum cylinder below. Just flat with no firing pin groove or rim around the edge and of course it's fluted.

 

[Hondo44]

The cylinder opening for Ruger's OM Single-Six and NM Single-Six were the same, so the cylinder lengths for all those cylinders are pretty much the same, but as rugerguy says, some will just drop in and others need a little extra filed off the front cone in order to fit.
Ruger got rid of the firing pin groove in the LR cylinder and began rollmarking an unfluted cylinder for the Mag. in late 1975 for the blue guns. For the stainless, these changes happened in mid-1976.
Chet15

Also I have two stainless 22s '75 and '76 vintage, that have a LR cyinder with the firing pin groove and rim around the circumference and the non-fluted Mag cylinder. So are they both in the transition period with old style LR cylinders and new style Mag cylinders.

My 2005 .22 has both cylinders with flat rear surfaces and non-fluted Mag cyl.