Model 66 - Cylinder Over-Rotation on Fast Trigger Pull

So I just opened up my baby and went to town on it:

Oversized hand, oversized cylinder stop, endshake bearings. It locks up better, no longer is out of time on a slow trigger pull, and has almost no endshake to speak of...

but, and this is a big butt, now when I pull the trigger fast it sometimes skips a stop and fails to lock up.

My guess is that I need to file the hand down a bit, but want to make sure before I do that. Also, maybe an issue, the hand I received hand an extra pin like thingy (that seems to not be interfering). Thirdly, maybe a stronger cylinder stop spring would help to be sure.

I know it should be an easy fix, but I wanted o ask the hive before I dig myself deeper into a hole.

I forgot to mention, I also added a lower power rebound spring, but I doubt that is the issue either.

Sounds as though you may be experiencing something similar to 'Throw-By', which is when the cylinder stop ball gets stuck under the frame and can't rise up to engage the cylinder's stop notches, so the cylinder spins until it loses energy.

'Over-size' cylinder stop, huh? How much over-size? Maybe it doesn't fit in all of the cylinder's stop notches, or is getting stuck trying to rise through the frame window? Offset a little in relation to the frame window and is sometimes getting trapped inside the frame? Dunno. What was wrong with the original cylinder stop?

Did you see whether the cylinder stop was visible above the frame when this happened?

Did you get the little mouse trap spring for the cylinder stop installed correctly when you were doing all your "smithing'?

Might be time for an actual gunsmith to take a look at the revolver.

Welcome to the forum, BillyJack2050.

1) Lower power rebound spring is an unlikely culprit.
2) If the cylinder stop spring you have is stock and correctly installed, that should work well; a stronger one, i.e., non-standard, invites other issues like excessive rub and wear.
3) The "extra pin like thingy" on the hand is, to the best of my knowledge, a feature used on hands in magnums that helps the hand hold position under the greater magnum recoil.

I'm assuming that since you're asking these questions, and your working on your revolver has introduced a significant problem (especially if you depend on it for anything serious) that you're probably not very experienced with working on S&Ws.

Nothing wrong with that, fine to learn and everyone who wants to learn has to sacrifice some gun somewhere to do it.

But...

If this is your primary or only defense handgun, get thee to a qualified S&W revolversmith and let him get it in proper working order.

While you're waiting for its return, buy yourself the Kuhnhausen S&W Shop Manual and study it closely; then start investing in the proper tools.

Even something as simple-seeming as fitting a hand correctly requires an informed and deft touch...

Fastbolt said:

Sounds as though you may be experiencing something similar to 'Throw-By', which is when the cylinder stop ball gets stuck under the frame and can't rise up to engage the cylinder's stop notches, so the cylinder spins until it loses energy.

'Over-size' cylinder stop, huh? How much over-size? Maybe it doesn't fit in all of the cylinder's stop notches, or is getting stuck trying to rise through the frame window? Offset a little in relation to the frame window and is sometimes getting trapped inside the frame? Dunno. What was wrong with the original cylinder stop?

Did you see whether the cylinder stop was visible above the frame when this happened?

Did you get the little mouse trap spring for the cylinder stop installed correctly when you were doing all your "smithing'?

Might be time for an actual gunsmith to take a look at the revolver.

Click to expand...

Thanks for your input. I did check to make sure the cylinder stop was exiting the frame, but forgot to mention that. I have been following 500 Magnum Nut's FAQ, and he points that out.

My old stop had too much play in it and this new one fits all parts (the window, and stops) much better. And when it fails to stop correctly it does exit the frame smoothly.

What I see happening is that there is a lot of torque now that the hand is engaging the ratchet fully and it gets the cylinder spinning fast.

Hapworth said:

Welcome to the forum, BillyJack2050.

1) Lower power rebound spring is an unlikely culprit.
2) If the cylinder stop spring you have is stock and correctly installed, that should work well; a stronger one, i.e., non-standard, invites other issues like excessive rub and wear.
3) The "extra pin like thingy" on the hand is, to the best of my knowledge, a feature used on hands in magnums that helps the hand hold position under the greater magnum recoil.

I'm assuming that since you're asking these questions, and your working on your revolver has introduced a significant problem (especially if you depend on it for anything serious) that you're probably not very experienced with working on S&Ws.

Nothing wrong with that, fine to learn and everyone who wants to learn has to sacrifice some gun somewhere to do it.

But...

If this is your primary or only defense handgun, get thee to a qualified S&W revolversmith and let him get it in proper working order.

While you're waiting for its return, buy yourself the Kuhnhausen S&W Shop Manual and study it closely; then start investing in the proper tools.

Even something as simple-seeming as fitting a hand correctly requires an informed and deft touch...

Click to expand...

Thanks too for your input! I liked the points to my particular questions, as they are very constructive.

I am also happy that you guys are worried about my gun, but I am not so much yet. I can always just reinstall the old parts and it will be just fine. Not rocket science, and this gun is much more straight forward than my others which I have already made much better (more reliable and smooth) by "smithing" them on my own.

I am just trying to get this gun working the best that I can. I mod my house, car, computer, and nearly everything else in my life, so why can't I work on my gun as well.

As of right now I am looking into ways to make the hand flip the ratchet a bit more gentle and with less inertia. 500 Magnum Nut suggests "dressing the ratchets" and this has already made a great difference on the smoothness of the DA pull. Seriously night and day.

I am thinking that the oversized hand and ratchet area is where my problem my lie.

Thanks again!

BillyJack,

You aren't going to like this, but I am going to be brutally honest with you in hopes of getting your attention! You don't have the slightest idea what you are doing and have no business being inside a S&W revolver! The hand, ratchet, trigger and cylinder stop are not drop-in parts, although the factory will sell them to you. You cannot just drop in a cylinder stop and hand and expect either to work properly.

First, the cylinder stop has to be fit to the trigger. It has to be adjusted so the stop is retracted to a certain point, no farther, when it is released by the trigger to allow the stop to rise. Once this is correct only then can you start to fit the hand for proper carry-up. I have been working on S&Ws for a long time and have seen just about every way that Bubba can screw one up. Fortunately most errors can be fixed.

Do yourself a favor. Either take the gun to a gunsmith qualified to repair S&W revolvers, not all are, or even send it to the factory. This will be, in the long run less expensive than to continue to guess what is wrong and continue to cut, whack and whittle on parts, and replace same, before finally lucking on to the correct combination. At the very least buy yourself a copy of "The Smith and Wesson Revolver, a Shop Manual" by Jerry Kuhnhausen before touching another thing on the gun. The book explains in detail the proper fitting each of the internal parts of the mechanism.

Alk8944 said:

BillyJack,

You aren't going to like this, but I am going to be brutally honest with you in hopes of getting your attention! You don't have the slightest idea what you are doing and have no business being inside a S&W revolver! The hand, ratchet, trigger and cylinder stop are not drop-in parts, although the factory will sell them to you. You cannot just drop in a cylinder stop and hand and expect either to work properly.

First, the cylinder stop has to be fit to the trigger. It has to be adjusted so the stop is retracted to a certain point, no farther, when it is released by the trigger to allow the stop to rise. Once this is correct only then can you start to fit the hand for proper carry-up. I have been working on S&Ws for a long time and have seen just about every way that Bubba can screw one up. Fortunately most errors can be fixed.

Do yourself a favor. Either take the gun to a gunsmith qualified to repair S&W revolvers, not all are, or even send it to the factory. This will be, in the long run less expensive than to continue to guess what is wrong and continue to cut, whack and whittle on parts, and replace same, before finally lucking on to the correct combination. At the very least buy yourself a copy of "The Smith and Wesson Revolver, a Shop Manual" by Jerry Kuhnhausen before touching another thing on the gun. The book explains in detail the proper fitting each of the internal parts of the mechanism.

Click to expand...

Well thanks for being honest! I did look at the stop, but not super close, and will look into timing it better (if needed).

And if you will... let me be a little honest as well. If I never got my hands dirty, and never went out on a limb, I would not be the amazing person I am today! I understand that you are just trying to save me the headaches, but one of the main reasons I am doing this it to learn.

I will buy a book (there have been two good ones already recommended), but the reason I started this thread was to find an answer to my specific problem.

There is no way the cylinder can spin past a properly timed and fitted cylinder stop. It's not the speed nor the hand at fault. I'm an inveterate tinkerer, but I know enough about Smith lockwork that I'm taking it to a pro. It is sufficient to know enough to judge when that step is necessary. In a recent thread, over half of the respondents thought that applying a little thumb pressure on the cylinder to check the timing (to keep it from locking up by inertia) was a gimmick to get a lower price. So much for advice from dilettante gunsmiths.

You may learn by experience, but experience comes from making mistakes (attributed to George Washington). With firearms, mistakes can be deadly.

Billy Jack: LOL, I 'like' you and your attitude. You will learn by doing, but it is very slow and expensive to do so on revolvers. Of all the 'guns' you have improved IMHO (and many others) the revolver design is the most complicated and difficult to get just "right" of all of them. If this handgun is important to you for target or self defense get a pro to fix it. IF it is just a working toy go ahead and bull around inside it. If you want to 'fix' S&W revolvers properly find a S&W Armorer's Class and attend it. Buy Jerry Kuhnhausen's book. We all started there. Jerry had an amazing ability to both put the words on paper where we laymen understood and he could do great photographs. Buy the correct tools. Then buy old junker pre 'Ks' or M 10s and start with them. I sure wouldn't begin my learning on a quality handgun like a M 66.

I have been working on S&W Revolvers for over 40 years and no way will I claim to be an expert. I still find conditions that stack together and baffle me. I go back to Jerry's book and reason out the symptoms that I am seeing, start with one, eliminate that one and go on to the next, etc. until the revolver is back in working order. The last thing you want to do is to throw a whole bunch of new off the shelf parts in and expect to know what is causing what part of the problems. IMHO, you are far better off to go with one part and one problem at a time.

If I read your OP correctly, I'm fairly sure that you don't have a good understanding of what is happening inside a S&W revolver when the trigger is pulled in DA. Remember, "Dykem" is the puzzled gunsmith's friend.

Good Luck. You are probably going to make a pretty good pistolsmith, someday. .......... Big Cholla

BillyJack2050 said:

My guess is that I need to file the hand down a bit,

Click to expand...

This sends up a big red flag. Makes me wonder if you watched the gawd awfull (and totally wrong) Larry Potterfield video...

It's easy to obsess on S&Ws over how much the cylinder "wiggles" and carrys up and it's easy to over do "tightening them up". These guns aren't Colts and aren't "tight" in "lockup" with the trigger back like a Colt. Relatively, S&Ws are "loosey goosey" and work best that way.

Sounds like you may have overdone with the OS stop and hand. Go back to stds. The stop needs to be somewhat "loose" to drop into the stop notches reliabley. The hand is better with timing on the "slow" side. "Fast" timing just puts the parts in a bind and wears them faster...

You'll find std hands actually have about a .003" variance if you mic a bunch of them. OS hands are rarely (but occaisionally) really needed. Fitting the OS parts may be a "feel good" thing but all too often gives the result you have, a gun that doesn't run.

Neumann said:

There is no way the cylinder can spin past a properly timed and fitted cylinder stop. It's not the speed nor the hand at fault.

You may learn by experience, but experience comes from making mistakes (attributed to George Washington). With firearms, mistakes can be deadly.

Click to expand...

If this is true, then it will be the stop where I will be focusing my attentions. Alk8944 offered up that the stop must be fitted first, which I did not, because it did not leave the window and pushed up about halfway through the cylinder rotation, and I may have wronging assumed that this was proper 'enough'.

When compared to my old stop the edge is a bit longer (and later), so I will be honing it down to drop sooner.

Not sure how doing this will risk my life, but I will be considering all options.

Thanks for the input!

Big Cholla said:

Buy Jerry Kuhnhausen's book. We all started there. I sure wouldn't begin my learning on a quality handgun like a M 66.

IMHO, you are far better off to go with one part and one problem at a time.

If I read your OP correctly, I'm fairly sure that you don't have a good understanding of what is happening inside a S&W revolver when the trigger is pulled in DA. Remember, "Dykem" is the puzzled gunsmith's friend.

Click to expand...

I am happy to buy that book ASAP, because I truly do love this revolver. Every time I look at it I get a glimpse and understanding of why and how our ancients could worship inanimate objects.

Really, I have no doubt that there is some of God's beauty in this revolver. And that is why I have begun the process of suping it up!

Once I have it working perfectly, I already have a set of meprolight night sights waiting here.

Thanks too for the Dykem advice. I have just been using a sharpie marker, but it may be time to upgrade considering.

Also, if I can say that I did make any mistake yet, it is that I threw all the parts in at once. I knew this would be an issue, but went for it anyway. Oh, well.

Honing the stop now...

I have a very qualified team of revolver-smiths at my full-time disposal, so I am very lucky not to have to work on any S&W these days. I can have a revolver to my gunsmiths the next day after any problem, and I have always had the problem fixed quickly, with little cost, and often they find some little something else, and fix it without me having to ask. It is easier than ruining a discontinued revolver, or one for which parts may be difficult to obtain. Feel free to get your revolver to my team. My team is located at 2100 Roosevelt Avenue, Springfield, Massachusetts. Just drop a note in the box, and give them some idea where to start, and they will get it right, in short order.

tomcatt51 said:

This sends up a big red flag. Makes me wonder if you watched the gawd awfull (and totally wrong) Larry Potterfield video...

It's easy to obsess on S&Ws over how much the cylinder "wiggles" and carrys up and it's easy to over do "tightening them up". These guns aren't Colts and aren't "tight" in "lockup" with the trigger back like a Colt. Relatively, S&Ws are "loosey goosey" and work best that way.

Sounds like you may have overdone with the OS stop and hand. Go back to stds. The stop needs to be somewhat "loose" to drop into the stop notches reliabley. The hand is better with timing on the "slow" side. "Fast" timing just puts the parts in a bind and wears them faster...

You'll find std hands actually have about a .003" variance if you mic a bunch of them. OS hands are rarely (but occaisionally) really needed. Fitting the OS parts may be a "feel good" thing but all too often gives the result you have, a gun that doesn't run.

Click to expand...

Thanks too for the constructive input. I did watch that Larry Potterfield. And let me tell you, he made it look easy!

I will stay away from attacking the hand too much. And if I am reading correctly, you are maybe suggesting a normal hand. I did need a new hand at least, because the old tip was deformed, causing a overly slow timing. And I did not what to just bend it back into shape.

I can see your point about too fast of timing and excess wear. Thanks, and I will make sure in the end it is still more on the slow side. 500 Magnum Nut's FAQ does hint about slowing down the timing by turning the OS hand into more of a normal size by thinning it up a bit on the inside side (if I am reading it correctly).

BillyJack2050 said:

500 Magnum Nut's FAQ does hint about slowing down the timing by turning the OS hand into more of a normal size by thinning it up a bit on the inside side (if I am reading it correctly).

Click to expand...

You are. Just thin the "tip". The part you see sticking thru the recoil shield with the cylinder open and the trigger held back. Thin the "inside", the center pin side.

I'd try going back to a std stop also. The MIM stops are usually a "drop in", not requiring "fitting" except to smooth their inter-action with the trigger for a smooth trigger return.

tomcatt51 said:

You are. Just thin the "tip". The part you see sticking thru the recoil shield with the cylinder open and the trigger held back. Thin the "inside", the center pin side.

I'd try going back to a std stop also. The MIM stops are usually a "drop in", not requiring "fitting" except to smooth their inter-action with the trigger for a smooth trigger return.

Click to expand...

Thanks for clearing up the fact that the tip is what should be resized. That was unclear in the FAQ.

Also, I just put in the old stop after de-burring the 'adjustment' lip, because the window had made some indentations over time which were allowing some excess side to side pivoting on the stop, translating to some wiggle room on the lock up.

The old stop has much less movement now. I may just use that for the time being until I can figure out how to reshape the OS one correctly (it is definitely needs work).

I'm not sure why you think you need an OS stop. These guns NEED (and are meant to have) cylinder rotational "wiggle". This allows the cylinder/chamber to "self align" when the gun is fired. Tightening up that rotational wiggle isn't necessary or desirable.

The stop / stop notch fit also needs to be loose enough the stop can reliably drop into the notch. Try to fit it "nice and tight" and it's all too easy to be "skipping chambers" as I think you've found...

tomcatt51 said:

I'm not sure why you think you need an OS stop. These guns NEED (and are meant to have) cylinder rotational "wiggle". This allows the cylinder/chamber to "self align" when the gun is fired. Tightening up that rotational wiggle isn't necessary or desirable.

The stop / stop notch fit also needs to be loose enough the stop can reliably drop into the notch. Try to fit it "nice and tight" and it's all too easy to be "skipping chambers" as I think you've found...

Click to expand...

I do really appreciate the help. And sorry for the lip. I just had all my gunsmithing dreams smashed just out the gate.

I am thinking I should go and handle a performance model (if that is possible). To feel how a real smith is supposed to feel.

Also, I should note: per Neumann's question, I think one could cause the cylinder to to skip just enough to have the pin strike the primer off center, making the bullet explode into the forcing cone. And my face. Scary.

Progress: I have found the both stops wiggle, with the oversize wiggling just a little bit less. The width seems to be bigger in body in general and not so much on the actual tip. The tip is much more elongated however. The gap where the window and stop are is about .006 (don't know if that is good or not), and will measure the notch and stop gap when I have it out again.

And when I sharpied the notch (Big Cholla style) to see where the stop hits it was too far towards the barrel. I am grinding from that way so that the markings scratch the deepest part of the notch.

And if it does not help, oh well. But I think it will.

I do have to admit that it is a harder gun to work on. Much harder. But will hopefully pay dividends in the future.

I'm def going to have to post a picture of it for you guys when I'm done. Making the metal brushed or whatever is the way I head with it. Pimped out style with hardwood handles. Bizzzaam!

One of the many old sayings some folks seem bound and determined to "rediscover" for themselves is ..

"Fix it till it's broken"

Negative nancys abound.

I have to admit how surprised I am to hear so many negative voices out there (not everybody). It was really disappointing.

Actually it is not surprising, the state our country is in, if you all, who are some of the last to pride themselves as real men, are so fear bound in your own lives.

I am of the next generation of citizens to take up the torch and fight for this way of life, and it is our generation who will have to relearn everything when all you leave us with your knowledge, unshared.

These days, who really cares about revolvers? And who will be left to teach us?

As a young guy, who is obviously not part of the old' boys club, whenever I go to guns shows I meet two types of people. One group is very helpful and excited to share their knowledge and passion for the art and hobby. The others are too caught up in their failing egos, looking smart and knowing everything to see really how dumb they look. Sorry to get all preachy like this but I am starting to get fed up with it.

Older, so called 'expert' men have told me so so so many things on all sorts of subjects that have turned out to be just plan bad advice. And meanwhile, offered up that advice in some of the most disrespectful manners. I put up with it out of respect for those who came before me, but it always hurts to do so.

Aside from that, and I am very thankful to those who spent their valuable time helping me. Even in the negative nancy posts I was able to glean lots of good info.

Update: After many hours of filing the OS stop into what I thought was the best I could do (just because I wanted to see what would happen), I found that the the original stop, with a smoothed out adjustment lip worked a lot better. No more skipping cylinders, and less play now.

I put the new OS hand in for a little better timing (not that much different from the original however). I rounded the baby off nice on a very distinct angle (found after meditating long and hard on the DA system) and this filled out the action so that the force is much smoother and equal throughout the trigger pull. Nice. I found that without the rebound spring in, all of the inconsistencies in the trigger pull become very feelable (and thus fixable).

I (carefully) mirrored finished many of the rub points. Installed the 11lb rebound spring. Put in end-shake bearings (using a feeler gauge to make sure they were needed) and finally installed the tritium night sights. And boy do they look nice.

All-in-all: Dealing with the OS stop was a lot of work and headaches for very little (actually no) improvement. I may have not needed the OS hand either, but having it there allowed me to play with the filing process without worrying about damaging the original 66-4 hand.

Pulling the thing apart and together several dozen times did cause some visible wear to gun, so that an expert would be able to tell a none-expert had been tinkering. I undoubtedly devalued the market value (but that is okay, because my grandkids won't be selling it either). But by the end I had the methods down so that I could disassemble and reassemble quickly without making a mark from now on.

Needless to say, it all got super cleaned and moly lubed.

And to those of you out there in posterity reading this (because I doubt any of those old farts above are), my point in being so wordy in my descriptions is that maybe you other noobs trying to find solutions will find this post useful.