Fix for extractor wear on the recoil shield? K frame model 66

[Art66]

I'm new to revolvers, and am learning as much as I can. I have some mechanical background but can only do minor gunsmith chores myself. I acquired a Model 66 no dash with some wear issues. Fixing the .0115" end shake will not correct the .013" barrel to cylinder gap. I've learned the barrel will need to be set back and forcing cone re-cut. However, the barrel is .125" shorter than the original 4". A gunsmith told me he will have to remove the barrel to see if any threads are even available to move it 1 turn back. It occurred to me that if the wear from the extractor turning on the recoil shield were repaired, the barrel to cylinder gap would likely be in spec. (difficult to measure the recoil shield wear, I guess a few thousandths) I know it's unlikely, just wondering if anyone has considered this and maybe even accomplished it? Most likely I would have to have a gunsmith make the repair. Just trying to bring this vintage pinned and recessed revolver back in spec while there are still gunsmiths that can do the work!

 

[Fishinfool]

Not all S&W 4 inch revolver barrels actually measure 4 inches on the dot. Slight variation is common. There should be plenty of barrel thread left to adjust the cylinder gap.

Without seeing the gun, its hard to imagine so much wear on the recoil shield / breach face that it would result in excessive cylinder gap, and I really don't know of any way to "build up" those areas, if they are that badly worn. Other may chime in with something I am missing.

Larry

 

[WR Moore]

There's generally negligible wear on the breech face from the extractor button. Your problem is most likely due to a combination of sloppy assembly once upon a time and heavy use. Possibly with a dash of assistance from someone who considered themselves to be a gunsmith.

You might contact the S&W service department to see what they might be able to do for you. If your endshake measurement is accurate, it might be best to replace the yoke with a new one.

Hint: if the barrel really was shortened 1/8 of an inch, your extractor rod and center pin have been shortened. Setting a barrel back one turn shortens the barrel and related items by 0.0277 inches. There should be plenty of threads left if the barrel wasn't shortened. If your gunsmith isn't aware of that, he might not be the best choice for repairs -unless he's got that 1/8 inch in mind.

 

[Art66]

Thanks for your thoughts!
My guess is the end-shake caused the wear to the recoil shield due to the cylinder slamming back during discharge.
The gunsmith is at what used to be the S&W western region service center and is very knowledgeable.
He will repair the end-shake by stretching the yoke shaft, in accordance with S&W recommended procedures. He did not recommend using washers. Finding a new or even a used yoke is a pipe dream for 66 no dash guns.
He was aware of the 3 7/8" long barrel when he stated he needed to check if threads were available for setting it back. I calculated the barrel could have been set back 4 times and be a little less than 1/8" shorter than the 4" original length. If the extractor rod was shortened they may have redone the knurling as well since it looks normal to me.
At this point I may as well send it out and hope the barrel can be set back. If not, I will just have the end-shake corrected and live with the excess B/C gap. The gun will still get dirty fast and have lower muzzle velocity, but it will still be OK for the occasional target shooting trips.

Just an additional note: S&W customer service told me that a 1973 model 66 revolver is obsolete and repair parts are not available. However she had the audacity to suggest that I ship it to them for a repair estimate. I have read forum member's accounts of revolvers being sent in and returned as being not repairable. That resulted in my search for an independent gunsmith.

 

[Hodado]

I have the same revolver and I sent it in to S&W for repair because the cylinder felt sloppy.I purchased it many years ago and believe it was a former law enforcement firearm.S&W had it for a couple months and did a nice job

 

[Art66]

Repaired at S&W

I have the same revolver and I sent it in to S&W for repair because the cylinder felt sloppy.I purchased it many years ago and believe it was a former law enforcement firearm.S&W had it for a couple months and did a nice job

Hey I'm glad they were able to fix your Model 66!
How long ago was it sent to S&W? I guess if it did not need an unavailable part they were able to fix it. Did they replace any parts, or just make adjustments?

 

[steelslaver]

The recoil shield to back of cylinder gap is critical. That head spaces the cartridge. If the excess end shake you have was somehow taken out on the recoil shield end of cylinder you would have a terrible head space problem. If your cylinder ratchet or recoil shield (the center of the ratchet rides on center of recoil shield) was worn enough that you had so much endshake your case heads would rub hard on the recoil shield when pressed rearward. .0115 is a lot of end shake! But, like WA Moore stated 1 turn is .0277 and every nbarrel I have seen off has a blank spot from end of threads to shoulder as do the frames. He will also have to adjust the slot for the pin a bit with a file

 

[Art66]

Questions for steelslaver...

The recoil shield to back of cylinder gap is critical. That head spaces the cartridge. If the excess end shake you have was somehow taken out on the recoil shield end of cylinder you would have a terrible head space problem. If your cylinder ratchet or recoil shield (the center of the ratchet rides on center of recoil shield) was worn enough that you had so much endshake your case heads would rub hard on the recoil shield when pressed rearward. .0115 is a lot of end shake! But, like WA Moore stated 1 turn is .0277 and every nbarrel I have seen off has a blank spot from end of threads to shoulder as do the frames. He will also have to adjust the slot for the pin a bit with a file

Thanks for your thoughts steelslaver. I recall that I eyed the headspace with the cylinder pushed back and it looked ample. I will put some spent cases in and double check it. Google did not give me any info on the spec limit or method for measuring headspace. Do you know the spec for headspace for a recessed cylinder? I'm sure the gunsmith will check it though when he does his initial estimate of repairs.
When you say adjust the slot for the pin, is that the pin that secures the barrel in place?

 

[armorer951]

Headspace (rear gauge) is .012"-.014" for the "magnum" cylinders. (checked with the cylinder empty...smaller (.012") is better)

 

[WR Moore]

The issue with stretching the yoke shaft is that it reduces the cross sectional area of the shaft. Since the yokes are now hen's teeth, this seems short sighted as this actually weakens the shaft. OTOH, if you use the washers, you can install new washers as needed.

S&W may have decided upon the stretching process umpteen years/decades ago. Doesn't mean there aren't better ways to do things now.

FWIW, I measured the 4 inch barrel on a 64-5 and it was 4 1/8 inches. As someone mentioned, actual length might depend upon production run.

 

[Art66]

I appreciate your thoughts on stretching the yoke. I had decided to try the washers, but changed my mind when I realized I do not have tools to clean up the end of the yoke shaft and the cylinder internal surface. The yoke shaft looks smooth on the riding surface but it is a narrow ring (less than the wall thickness of the shaft). I should look at the yoke shaft in my model 19 since it is in excellent original condition. If it looks the same I'll just use some .002" washers that I already purchased.

The headspace is great at .012-.013".

That is interesting your barrel is 4 1/8". Makes me wonder why they varied so much. Maybe different model numbers had slightly different lengths too.

 

[RMFnLA]

Smith & Wesson 66- .357- K Frame- Stainless Cylinder & Yoke- Crane - 2025 | eBay

 

[WR Moore]

Cleaning up the bottom surface of the cylinder center bore is easy. Get a piece of drill rod/round stock close to the right diameter, make one end square to the shaft. Glue a piece of emery cloth to the end and polish away.

If the end of the yoke barrel is square to the shaft, careful polish with a fine/medium stone will work. Gently break the interior/exterior edge with the same stone/counter sink/case chamfering tool. Remember, you're just trying to remove a sharp edge, so don't work too hard on the edge breaking.

Having said that and re-reading your last post the bearing surface at the end of the yoke shaft should be the full thickness of the wall. Perhaps Bubba the gumschmidt was at work.

You might want to jump on that item posted by RMFnLA. I once had to make a yoke bushing about 0.055 " thick to correct endshake on a caliber conversion done by a famous name shop.

 

[Art66]

WR Moore thanks for the great information. I did look at my model 19 yoke and noted the end bearing surface is wider. I tried to measure the depth of the interior bevel, guessing about .020". I don't have a tool to cut down the yoke shaft to remove the beveled area while keeping the end surface perpendicular to the shaft. A guy on youtube had one but I could not find one to buy online. I don't have a lathe so I could not make the cylinder resurfacing tool (from a drill bit) you described. Home Depot did not even carry any lettered drill bits.
I did check with a retired LEO friend that has done gunsmithing. He strongly advised against having the yoke stretched. He suggested a simpler alternative. So, as a temporary fix I smoothed the end of the yoke shaft with a fine stone, installed .008" of washers and ended up with .003" of end shake. It seems the cylinder bearing surface must be flat (pre-fix endshake was .00115"). Now it feels like a new gun! I don't know how well it will hold up though.
Regarding the ebay yoke and cylinder combo, it is different than mine. It has a gas ring on the yoke shaft. I'm not sure if it would work in my 66.
Regarding the barrel length, I re-measured it (this time from the crown to the end of the forcing cone) and it is 3 31/32". There should be no problem setting the barrel back. But I probably should not do that until I have the yoke and cylinder properly repaired.

 

[steelslaver]

With the end shake taken care of using hardened shims you should be alright for some time. If anything the end of the yoke tube might get slowly hammered shorter more than worn shorter. If this happens the end surface face will get wider.

A yoke and cylinder should work even if it has yoke mounted gas ring if used as a set. Installing your cylinder on that yoke would not work. But I think you'll be fine as is, although it would be nice to have a tighter B?C gap.

 

[Art66]

With the end shake taken care of using hardened shims you should be alright for some time. If anything the end of the yoke tube might get slowly hammered shorter more than worn shorter. If this happens the end surface face will get wider.

A yoke and cylinder should work even if it has yoke mounted gas ring if used as a set. Installing your cylinder on that yoke would not work. But I think you'll be fine as is, although it would be nice to have a tighter B?C gap.

Well that is encouraging information! I rarely go target shooting, so it should last me a long time. If the end shake increases from the yoke tube shortening it will be easy to add another washer. I may go ahead and have the barrel set back to get the B/C gap corrected.

 

[WR Moore]

Drill rod/round stock ISN'T A DRILL BIT! Come to think of it, given what you're doing, you could use a wooden dowel rod. But, looks like you may have worked it out. Lottsa luck.

 

[steelslaver]

drill rod is round tool steel available for places like Fastenal.

 

[Art66]

My bad...

Drill rod/round stock ISN'T A DRILL BIT! Come to think of it, given what you're doing, you could use a wooden dowel rod. But, looks like you may have worked it out. Lottsa luck.

Sorry, I was thinking of another member's post where he used a W size drill (?) with wet/dry sandpaper glued to the end.
Thanks for all your input and well wishes. I think it will work out OK for me at this point!