I have an extra 642 cylinder. I was wondering if there are any issues in swapping it the cylinder on my 342Ti? Are all j-frame cylinders interchangable?

regards

All revolver cylinders are fitted, and should be checked by a knowledgeable smith when switching to a different gun. It may work; it may not.

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Science plus Art

Revolvers are very Old School and are unlike automatics in that critical parts are very much hand fitted and adjusted.
No part is more fitted and adjusted then the cylinder assembly.
They have to be checked and possibly adjusted for barrel/chamber alignment on all chambers, cylinder end shake, head space, and timing on all chambers.

Just because a cylinder will snap into the frame is no sign it really fits or is even safe to shoot.

Thanks guys, thats good to know. I figured with modern CNC machining it would fit with similar models.

Mike, don't despair. It might work and most of the time it shouldn't take that much to fit it. A good revolver smith could check it and and necessary work.

You could install it yourself. See if it closes up. Does it latch in place, does it unlatch properly? Check the barrel to cylinder gap with fine feeler gauges, press the cylinder forward when doing so. Your looking for .004-010 when pressed forward. Tighter is preferred. Then press back and remeasure. The difference is your end shake. If more than .002 it can be eliminated with shims available from places like Midway. No check the head space. First make sure the extractor area is clean and it seats fully. On a non recessed cylinder it should be between .060 and .074 between the cylinder and where the firing pin comes through for the head space, press the cylinder forward when doing so after eliminating any excess end shake. Check each chamber. They make go and no go gauges for this, but feeler gauges will work. You just measure the gap or can take a FIRED case and measure its rim carefully then use a feeler gauge between it and the frame. Cycle it very slowly and make sure it locks up before the hammer locks in single action and before it drops in double. Now does it skip or fail to lock up when cocked rapidly? Does the cylinder stop come all the way up into each slot? Now you need a range rod to check for alignment. This is a tool that just slides down the barrel with minimal clearance to the lands of the rifling and should drop into the chambers when locked up. Try it on each chamber and while pressing the cylinder both rotational directions. A couple of thousands movement is normal. Compare it to the original cylinder. If it passes all these tests it should be good to go. If not a good smith should be able to adjust it to work. He should have both cylinders when doing so.

Steelslaver - thanks for the very informative and detailed post. This should be a "FAQ" for future use. I'll just need to get a range rod and I should be good to go. Thanks again for everyone's advice!

regards

If you are going to try it, use the original yoke, ejector rod and ejector star. The odds are quite a bit better it will fit and work.

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H Richard
SWCA1967 SWHF244

I've got a couple model 36's with nice frames and bunged up cylinders, and a couple vice-versa. I've tried on a couple occasions to swap cylinders between them with no luck. Tried to swap extractor assembies between cylinders once and even that didn't work out well.

double post sorry

Some cylinders are different lengths than others, some have a slightly different depth of the bore that that the yoke slides onto. They change somethings on different models and revisions. They are not all going to just pop in. Sometimes they do and sometimes they don't. Some are easy to adjust some take more or are not worth the trouble.

What problems did you run into??

I currently have 3 revolvers with 2 cylinders each. 2 45acp/45LC and one 38/357. all where fairly easy to adjust. I personally use a separate yoke for each. Fitting those can be a problem in itself.

If you have to slightly shorten the yoke tube for a new cylinder assy, you will have to shim the old cylinder assy. This occurs when the new cylinder just barely runs into the forcing cone and has a large head space and needs set back a bit. Some cylinders are longer than others on the barrel end. 44 mags and 45 LC over model 27 and 28s and 45 ACP. K frame 357 are longer than most 38s. For some examples. A recessed cylinder will hit the frame lug on a non recessed cylinder frame. There are may reasons it may not just go right together. Some can be fixed and some not. Some are easy some take more equipment and work.

Do you want to sell a nice frame and cylinder that don't fit together. Been a while since I had a J frame

One thing I have learned with S&W is they like to change some dementions on their parts when they make model upgrades. I have a model 10-7 that has a bad nickel finish on the cylinder. I found a 10-5 nickel cylinder that would not come even close to fitting. I have had other parts fitting problems also.

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Tom
NRA Pistol Inst

When I worked in the ordanance dept I had a new guy who thought separating the cylinder from the frame would make them safe from theft. The problem he did not mark or record what went with what. After 2 weeks of failure to fit the revovlers, out of frustration the boss destroyed them.
That was 12 perfect Model 15 Combat Masterpiece's !

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JIM
NRA Pistol Instr

We if he was that dumb I am sure he couldn't have figured it out. But, there would even be that many combinations with only 12 guns of the same model. I would have had 12 perfect model 15s

I've had good luck....as long as you "stay within the family and caliber". Such as the 60, 640, 649, 38...etc. Smith did change extractor configurations from time to time, but often....if you swap the ENTIRE assembly (crane, cylinder, center-pin, ejector rod and extractor)....it will work, but you have to stay within the same yoke retention family as well. I've built more than a couple of Palomino's. Why....heck I don't know. Because I could I guess and there are plentiful spare cylinders lying about out there. Just like already mentioned....timing, BTCG, end-shake, etc. has to be checked.

12 guns and 12 cylinders give you 12 squared different combinations. That 144 different possible combinations to start. Every one you match up dramatically reduces the remaining possible combinations. After you match just one the possiblities drops to 11 squared (121), then 10 squared (100) after 2 are matched, 9 squared (81) after 3 matches are found etc.

It's a shame that folks like me who have plenty of time on their hands could not have been "handy" to beg those parts before they were crushed. A virtual Rubik's Cube of gun assembly.

You may have ended up with some that had real good fit up and a few poor as you may have got some to improve.

I would have started out by carefully measuring all the cylinders (height of ratchet too) and then all the frames to forcing cone.

It would have been more fun if he separated all the yokes from the cylinders and the frames. Some cylinders will not slide all the way on some yokes and some yokes don't fit all frames perfectly.

I am sure you could have came up with some really well fit units and may have ended up with 2 or 3 parts guns.

What a tragedy.