I have a 66 no dash that has a 0.010" gap between the forcing cone and the cylinder face when the cylinder is pulled rearward. I haven't seen evidence of any lead spray, but there is more smoke than from my 67 no dash with about 0.003" gap. I called S&W and was told that a proper fix would involve removal of the barrel and machining the forcing cone. Because of the age of the revolver there would probably be a charge of $200 and a 3 to 4 month wait.

I saw a video from Midway USA explaining a fix with shims that sell for $15, and the procedure seems fairly straight forward for anyone with adequate mechanical skills.

I would like to hear opinions as to whether this second option would be a satisfactory choice of options.

I've used them on a few S&W revolvers with excessive endshake in years past with good results. Follow the directions in the packaging. They are available from Brownell's. A search on this forum will provide lots of good posts on what is considered excessive endshake and how to fix it. A more extensive fix for endshake can be found in Kuhnhasen's excellenet book on S&W Revolvers.

Yoke Endshake Bearings, Smith & Wesson K, L, N only : CYLINDER BEARINGS | Brownells

The S&W Revolver A Shop Manual: Covers the S&W J, K, L and N Frame Revolver Actions: Jerry kuhnhausen: 0715889000019: Amazon.com: Books@@AMEPARAM@@http://ecx.images-amazon.com/images/I/41itQm2d19L.@@AMEPARAM@@41itQm2d19L

I can't of the top of my head, remember what the maximum acceptable distance is between the f/c and cylinder, but I think .010 is right there. If you shim it or have the yoke stretched, you will create more distance there. Really, the correct fix is the barrel removal/machining method.

Are you worried about the end shake or BC GAP? A .010 BC gap is fine. Some obsess about BC gap, but it really affects shooting little up to around .015", as long as it is even.
END SHAKE is the difference between the BC gap with the cylinder pushed forward and the BC gap with the cylinder pushed back. THAT is what can be cured with the washer shims. Washer shims do not change the max BC gap with the cylinder pushed back.

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Science plus Art

Here's some good information on the subject posted by dfariswheel on another forum:


"Cylinder end shake is the amount the cylinder is free to move back and forth in the frame. What might look like a barrel/cylinder gap problem might really be end shake.

First step is to measure for end shake.
To do this push the cylinder to the rear and hold it there while you use an automotive feeler gage set to measure the gap between the barrel and the cylinder.
Then push the cylinder forward and hold it while you gage the gap again.
Subtract one measurement from the other and that's how much end shake the gun has.
S&W specs are that an end shake of "about" 0.006" or more needs repair.

Note that the measurement with the cylinder to the rear is the actual barrel/cylinder gap.

S&W has radically loosened the factory specifications on barrel/cylinder gap.
Years ago a gap of around 0.005" was about perfect, and a gap of over 0.008" was out of spec.
S&W has loosened this to anything under as much as 0.012" being "in factory spec".
S&W has determined that the larger gap has little real effect on velocity, accuracy, or on spitting bullet metal on a gun that's in correct factory barrel/chamber alignment.

In other words, send a S&W back to the factory with a gap under 0.012" and S&W will return it as in spec."


And from another excellent post by dfariswheel on another forum:


"First, here's how to measure it:

Gently push the cylinder to the REAR and HOLD it there.
(Don't use a lot of force, just hold it to the rear).
Use an automotive feeler gage to gage the barrel/cylinder gap.
(This is also the ACTUAL barrel/cylinder gap).
Then push the cylinder FORWARD and hold it there while you again gage the barrel/cylinder gap.

Subtract one measurement from another, and that's how much end shake you have.
These specs are valid for S&W ONLY, NOT Colt, Ruger, or anyone else:

Maximum end shake: "About" 0.006" or more. (S&W has gotten rather vague on this in the past few years).

Barrel/Cylinder gap: Maximum of "about" 0.010". (Again, S&W seems to have loosened specs).

"Perfect" barrel/cylinder gap: 0.005".

So, if you gage your S&W end shake at over 0.006" it needs repairs.

DO NOT confuse the measurement with the cylinder forward as true barrel/cylinder gap. That's a false reading and may indicate too LITTLE gap.
True barrel/cylinder gap is with the cylinder to the rear."

I just watched the you tube video of Larry Porterfield using the bearings to reduce end shake. He measures the B/C gap as 0.010" before inserting the bearings, and shows the negligible movement after, but does not re-measure the B/C gap. This seems to validate the comments about what the bearings do and don't do.

They just did mine for $103 and this included return shipping

Make sure that if you use shims it doesn't affect head space? Have you checked that? This is the measurement at the back end.There are happy mediums. What kind of accuracy are you getting from this revolver, now?
Steve

How long did it take?

The accuracy is equal to that of my 67 no dash, which has less of a gap. However, there is more smoke from the 66.

They have had it for two months and told me ill have it back within two. So 4 all together.