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Thread: "Fitting" a SA Cylinder to a Gun -- What's Involved?

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    Member Scorpion8's Avatar
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    Default "Fitting" a SA Cylinder to a Gun -- What's Involved?

    I have a Puma 22LR 1873 SA revolver that is a ton of fun. I found that they also offer a 22WMR cylinder for the gun, but Chiappa wants me to ship the gun to them to "fit" the cylinder to the gun. Considering modern manufacturing techniques, shouldn't parts from one Puma 1873-22 be basically identical as another Puma 1873-22? What's involved in "fitting" a cylinder to the gun? I assume they mean making sure the timing is right between cylinder rotation and barrel alignment, but that's set when you cast the ratchet into the cylinder.

    I'm trying to get them to sell me the cylinder and ship it here (there are no gunsmiths in Juneau) so I can bring it to Anchorage one day and have the cylinder "fitted" as it were.

    Any help from any of the pistol 'smiths?

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    Supporting Member iofthetaiga's Avatar
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    Quote Originally Posted by Scorpion8 View Post
    I have a Puma 22LR 1873 SA revolver that is a ton of fun. I found that they also offer a 22WMR cylinder for the gun, but Chiappa wants me to ship the gun to them to "fit" the cylinder to the gun. Considering modern manufacturing techniques, shouldn't parts from one Puma 1873-22 be basically identical as another Puma 1873-22? What's involved in "fitting" a cylinder to the gun? I assume they mean making sure the timing is right between cylinder rotation and barrel alignment, but that's set when you cast the ratchet into the cylinder.

    I'm trying to get them to sell me the cylinder and ship it here (there are no gunsmiths in Juneau) so I can bring it to Anchorage one day and have the cylinder "fitted" as it were.

    Any help from any of the pistol 'smiths?
    Cylinder face to barrel end fit, and 'end shake' clearances both need to be individually fit, even (or especially) with "modern manufacturing techniques". Proper timing and lockup need to be checked too. Having the factory do the work will ensure the warranty remains valid.
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    Quote Originally Posted by iofthetaiga View Post
    Cylinder face to barrel end fit, and 'end shake' clearances both need to be individually fit, even (or especially) with "modern manufacturing techniques". Proper timing and lockup need to be checked too. Having the factory do the work will ensure the warranty remains valid.
    What he said, they come a little long and need fitting for end shake. Not hard to do but it will not just drop in. Gap will likely fall wherever it falls on a switch cylinder unless they leave that long too, Ruger and S&W donít, itís a standard length on theirs and gap adjusted with barrel. Timing is a product of the locking pawl, should be fine but needs checked anyway.


    Best advice is let them at it if you can work out the shipping issues for a handgun in Southeast Alaska.
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    Guess I'm having a hard time with these replies, or perhaps it's just my misunderstanding. If any one cylinder didn't fit on every other identical gun of this make/mode/production version, then we're right back to the hand-custom-made flintlock days of zero parts interchangeability. All my 98 Mauser bolts fit in each others receivers without the need to re-headspace the barrel for each bolt, or re-set the trigger sear. Makes no sense that one cylinder in a Puma 1873-22 wouldn't fit and be timed correctly in every other Puma 1873-22 that came off the production line at the same time, as well as being able to swap grips, cylinder rods, etc.

    I'm not seeing the daylight here, guys.

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    Supporting Member iofthetaiga's Avatar
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    Google "manufacturing tolerances"....
    ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
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    You canít be swapping bolts around on your rifles ether, sure it will go in but chances are it will not headspace the round correctly and you will need a gauge set to know if you have excessive headspace. There is a reason they are usually numbered to match the rifle, the receiver, bolt, and barrel are together when the chamber is cut and they are meant to always stay a set from then on.
     
    The way you are thinking (every part identical) is imposable to do and have a tight fit. It can be done by making parts under and over size slightly but that will give some guns an unsafe sloppy fit as tools wear and are replaced.
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    "I", I know all about manufacturing tolerances, but .... So each and every one is fine with your next AR upper needing to be hand-fitted to your AR lower, and then it not being available to swap to any other lower? That's the whole point of modern CNC manufacturing. You'd never accept that in your AR's or your 10/22's. You'd never accept magazines that had to be hand-fitted to each 1911 and then couldn't be used in any other 1911. Yet everyone expects this case to be just oh-so-normal.

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    Supporting Member iofthetaiga's Avatar
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    <sigh> Best luck to you friend.
    ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
    I would rather have a mind opened by wonder than one closed by belief. ~Gerry Spence
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    Quote Originally Posted by Scorpion8 View Post
    "I", I know all about manufacturing tolerances, but .... So each and every one is fine with your next AR upper needing to be hand-fitted to your AR lower, and then it not being available to swap to any other lower? That's the whole point of modern CNC manufacturing. You'd never accept that in your AR's or your 10/22's. You'd never accept magazines that had to be hand-fitted to each 1911 and then couldn't be used in any other 1911. Yet everyone expects this case to be just oh-so-normal.
    Not meaning any disrespect but if you know why ask. Itís quite evident that you do not know or understand. AR was designed in the 1950s and 60s with different methods to account for headspace and so on. Revolvers and Mausers were designed in the 1800s with hard fixed points controlling headspace that are only adjusted by cutting something, they canít be one size fits all because they were not designed with that in mind.
     
    Now, some advice. Open your mind to the answers you get to your questions and educate yourself before you earn a Darwin award or get someone around you heart!
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    Quote Originally Posted by ADfields View Post
    Itís quite evident that you do not know or understand. ......and educate yourself before you earn a Darwin award or get someone around you heart!
    The difference here is I know, and you just accept. You accept the bs that somebody tells you, because you don't have an independent thinking mind. This started off as a simple question. And I assume your spelling is as poor as your logic, because otherwise that last sentence is the dumbest ever.

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    Oh, and no disrespect intended. Snort.

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    Supporting Member iofthetaiga's Avatar
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    Ask a question of a gunsmith; receive an honest, accurate answer from a gunsmith; respond by being arrogant, argumentative and snarky. Classic.
    ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
    I would rather have a mind opened by wonder than one closed by belief. ~Gerry Spence
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    Okay big guy, you told me . . . Now please consult another provisionalís second opinion before you do something to yourself or someone around you and spend the rest of your life regretting.
    Andy
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    Quote Originally Posted by iofthetaiga View Post
    <sigh> Best luck to you friend.
    I'm VERY afraid he's going to need it . . . . .

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    Quote Originally Posted by iofthetaiga View Post
    .... receive an honest, accurate answer from a gunsmith; ....
    Actually, I never did receive an answer. I had my knowledge of manufacturing tolerances questioned although nobody here knows my background, experience, or pedigree.

    Quote Originally Posted by ADfields View Post
    Now please consult another provisionalís second opinion before you do something to yourself or someone around you and spend the rest of your life regretting.
    To continue above, let's examine the actual question. I can buy a Chevy 350 and replace the pistons, and I do *not* need to buy 10 pistons for a V-8 and test try fit each one to find the ones that fit. But I do have to do this with a Puma cylinder. I can swap bearings and blades on a GE LM-2500 gas turbine, and every part off one turbine fits onto another turbine. No hand fitting involved. But I do have to hand fit a Puma cylinder. I can buy any AR-upper and it will fit on any other AR-lower, in fact was designed to. But I cannot with a Puma 22LR cylinder. I can buy any two rifles of any caliber and they will have identical bores out to several hundreths of thousandths of an inch tolerance. But I cannot expect a Puma cylinder to fit with any reasonable cylinder gap at the rotating pin?

    These are the obvious questions that all you experts have over looked, and that nobody has answered. Is the manufacturing just "that bad"? That's an answer I can accept. If this was a vintage 1700-flintlock where every piece was handmade, that's an answer I can accept. Instead of telling me I don't understand manufacturing tolerances, while you can't tell me why they can hold the tolerances true in every example cited "except this one", understand that I do know manufacturing tolerances. Nobody has adequately answered why I can swap around every other piece of machinery except this one? That's all the cylinder is, is a rotating part that has to be held within several thousandths of an inch such that the rotating pin gap and forcing cone gaps are within spec, They can do it for gas turbines and modern internal combustion engines, but they can't do it here?

    Now do you see why it makes no sense, experts? No reasonable explanation has been advanced. Maybe Chiappa Firearms doesn't use CNC equipment, maybe they use trained monkeys. Again, an answer I can accept. But their 22 bores are all identical, so they are doiung something else "within tolerances".

    Now can someone explain why a Puma cylinder must be hand-fit, and a GE LM-2500 turbine blade that rotates at 36,000-rpm doesn't?

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    This post is in no way intended to offend anybody, especially not gunsmiths - and in particular not Andy, who currently is in possession of, and doing work on, one of my rifles.

    Scorpion, if you have some time, search the 'Net for fitting a cylinder to a Ruger Single Six. That revolver has been made since the 50's and has has it's share of model changes over the years, and it's typically come with two cylinders - cylinders that get lost over time. There are a metric ton of posts on gun forums about whether or not it's a good idea - or if it's even possible - to use a replacement they bought from somewhere like ebay, and whether they should have it fitted by a gunsmith.

    Most of the replies are just like this one; they do need to be fitted. But, if you read past all of the standard answers, you may come to the conclusion that - in the vast majority of cases - the replacement cylinder does not actually need any fitting work to function just fine. In fact, there are plenty of posts about using current generation cylinders on 1st generation, or other early frames. It's done all the time. New chrome cylinder on a old blued frame? Yep - and without any actual "fitting".

    So, yes. It can be done, and is done all the time. But, I would urge you to be cautious here. Although there are many, many stories of success when replacing cylinders in convertible revolvers, there are also a few stories of failure. So, if you don't want to send your gun in to the manufacturer so that they can retain liability for the change in configuration, at least check the fit if any replacement cylinder you may acquire before using it (most laymen have the skills and tools available to check a revolver for proper function). And, if it doesn't fit properly, either sell that one and find one that fits better, or have that one properly fitted by a competent gunsmith.
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    Ok, I'll bite

    Let's start using some of your examples.

    The AR-15: there are no critical dimensions between the upper and lower. The lower may loosely fit the upper, and as long as the hammer hit the firing pin, it will work. The critical dimensions are all either totally within the lower (fire control group), or the upper (bolt- barrel headspacing). If you change out components of the fire control group, they should be fit, and if you change out the bolt, it should be fit for headspace.

    The Chevy 350: there IS slop and variations between different pistons. Just measure your ring gap next time, there is variation that is taken up by the rings.

    Turbines: at least in my experience with replacing blades, they have to be installed as a matched set, or blended/ fit, and balanced. This at least is the case in the GE T700 and the PW F117.

    What manufacturing technique does Chiappa use? Cast? Forged and milled? I don't know, but each has Greatly different tolerances.

    How much does that Chiappa cost? As much as a turbine blade? How many generations of Chiappas are out there? Is it the same EXACTLY as one manufactured 40 years ago as one made today?

    How much frame stretch has occurred on yours vs a new one? You know they do stretch right? How many heat cycles has yours been through vs the next guys?

    Just a .001 variation in cylinder gap makes a difference on a revolver. There are too many variables out there to just send them out the door as "drop in" for the customer to get a quality replacement job.
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    Was never my intent to get into a peein match. You asked, we answered with the way it is, things are the way they are like it or not. I donít run the world so I canít help if you donít like the way things work all I did was try to explain some of it and get flamed for my effort. BTW no I canít spell worth a hoot but Iím a machinist/gunsmith not an English professor.


    Any new replacement cylinder you get will be deliberately made over size in critical diminution. In critical detentions we are not dealing with ďa couple thousandths of an inchĒ but ten-thousands or ten times less than you are thinking. Replacements are made oversize so that they can fit a brand new gun or one nearly worn out. If they made them all one size it would need to be at the small end of tolerance to fit all new guns and if the new gun happens to be on the large side of tolerance it would have excessive end-shack in no time . . . Put that short machined cylinder on an old gun that has wear and you start out out of speck. Therefore, for all these reasons of tolerance all new cylinders are made long so that they can be fitted to any gun for a good fit on that particular gun. It's just like Chevy 350 piston rings come oversize and need to be gapped (hand fitted) to each cylinder wall so the fit is tight at operating temperature.


    Now chances are good that if you buy a used cylinder that was factory fitted to another frame it would drop in and function. Fair to middling that it would be within acceptable tolerances even but slight chance that it will be as tight and last as long as a cylinder properly fitted to your frame. Then, if your frame was loose and the one the cylinder came from tight it wouldnít fit without fitting it just like a new one.


    The revolver stuff is minor on the safety scale, you are not likely to injure someone by poorly fitting a cylinder . . . Ruin the parts yes, not function sure, explode the gun not very likely. The same is not true of swaping bolts on rifles, sticking a bolt from one Mauser rifle into another can and has killed people, don't do it!!
    Andy
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    Quote Originally Posted by Scorpion8 View Post
    The difference here is I know, and you just accept. You accept the bs that somebody tells you, because you don't have an independent thinking mind. This started off as a simple question. And I assume your spelling is as poor as your logic, because otherwise that last sentence is the dumbest ever.
    The difference between you and Andy in this post is that Andy has been involved with firearms and gunsmithing for years and you have not. The TRUTH is that he knows by having done what you ask and you are imagining it is so. You shouldn't confuse your imagination with reality..............
    Foolishness is a moral category, not an intellectual one.

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    Member Rod in Wasilla's Avatar
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    Good point regarding new (never been fitted) vs. used (previously fitted to something), Andy. And if new cylinders are, in fact, made oversized and then factory fitted, it makes sense that the factory won't sell cylinders without fitting them to a particular frame.

    But, I think that Scorpion's angst is about why manufacturers couldn't/wouldn't refine their processes to the point that such hand fitting wouldn't be necessary. To that, I would offer this. Even if modern manufacturing techniques could allow production of many thousands of identical parts (which I do think is possible - but can get very expensive), there is no way for a manufacturer to know that such refined modern parts would not be used on less refined older guns. Therefore, even if strictly due to liability issues, it is necessary for gun makers to confirm that any critical new parts are properly fitted and installed.

    It's not a big deal, really. Either way, it's the policy of the manufacturer to require fitting for a new cylinder. So, if somebody wants NEW, they have to send their frame in and have the cylinder properly fit. It will come back with the knowledge that it was done right, and the manufacturer must accept liability if there is ever a problem. If USED is OK, proceed with caution, and with the expectation that there may be some fitting necessary. Again, not really that big of an issue in my opinion.
    Quote Originally Posted by northwestalska
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