Model 60 cylinder rubbing the barrel end

[cjtraining]

I have Model 60, R serial number, that I bought on Gunbroker. I cleaned the gun of any residue, burnt powder, completely disassembled it, etc. The revolver looked showroom ready. I took it to the range and shot a box of .38 Federal hollow point, blue tip, no +p. The cylinder seemed to function properly. When I took the cylinder out of the frame for cleaning, I noticed there were scrape marks on the top of each hole. The end of the top of the barrel was also marked. My gauge would not pass between the cylinder and the barrel end. It appears to me the barrel end and the cylinder face are scraping. What will it take to make it right?

 

[armorer951]

You either have excessive end shake, or the front gauge or "b/c gap" as it's sometimes called, was not fit correctly when the gun was manufactured.

I would guess by the age of the gun that end shake has caused the cylinder to move forward slightly on the yoke. This is just wear and tear on the assembly, which causes the cylinder to move forward. Be sure to check for end shake on the yoke itself to. The yoke should not move forward and back when it is installed in the gun and it is in the closed position. The yoke screw secures the yoke properly in place.

You can check the amount of end shake on the cylinder by closing the cylinder and the pulling back on the cylinder body and measuring the b/c gap with the cylinder pushed back. (against the breechface)
If the front of the cylinder is in contact with the bbl extension when it is closed, then this measurement (b/c gap when cylinder held fully rearward) will tell you the amount of end shake present. You can do this with a set of feeler gauges. Remember though, you need some gauge in the cylinder assembly for it to work as designed. (open and close, and turn freely) You don't want to remove all the endshake present in the assembly.

The yoke barrel can be stretched, but the easiest way to return the cylinder back to it's proper location is with shims. End shake shims are available to move the cylinder back into it's proper position, and can be ordered in different sizes. (thicknesses)

Cylinder shims or "end shake" shims are available here:

TriggerShims Brand Gun Shim Kits, Gun Shim and Spring Kits

Be sure to measure first, then order the necessary shim or shims to remove all but approx. .001" - .002" of the end shake that is present. If you have .005" of front to back movement in the assembly when the cylinder gap is measured with the cylinder held back, you'll need approx. .004" in shims. perhaps an assortment of .001" and .002" ones. The shims are installed inside the yoke cavity in the cylinder.

 

[robertrwalsh]

Assuming the problem is the b/c gap and not end shake it is not hard to correct, but purchasing the tools to do so is an investment. It is much easier and less expensive unless you plan on doing it a lot to pay a competent gunsmith to correct the problem. Start with diagnosing the possible end shake problem. It is (as noted above) very likely there and even easier to correct most of the time.

 

[steelslaver]

I actually like the shims better than the stretch the tube method. With the ships you end up with a really smooth hardened surface fro the tube and cylinder to space with.

Make sure that the area between ejector star and cylinder are completely clean with no sneaky carbon to hold the star from completely seating before anything else. If that is clean clean and the face of cylinder touches while held or shimmed back to minimal end shake you may need your barrel extension trimmed just a bit.

 

[MP-5]

 

[MP-5]

Because it works!

 

[steelslaver]

I have the tool to trim the barrel extension, cutt forcing cone and lap it. But I often just use a fine file with safed edges (no teeth) instead. Usually I am working with a barrel I just fit. Once the cylinder will close I hold it up to a light and press the cylinder forward. Wearing an optivisor you can see if there is a spot that touches or use a thin feeler gauge and find the tight spot. Then hold the file with more pressure on side or top bottom. You can file perfectly flat. It is a mater of actually knowing how to use a file correctly.

I also took a set of feeler gauges from .002 to .010 and clamped them tightly together and took them to my belt grinder with a fine belt and made them only about 3/8 wide. Some sets will not pass though between the frame and gas ring on J and K frames. This set will and allows you to check for any difference between top and bottom gap.

I am going to fit a model 15 barrel on a J&G frame I installed adjustable rear sights on today. That will be J&G frame #5 that is now a functioning gun again. I have decided the last one will become a 6" 327 Federal

 

[bgrafsr]

I have the tool to trim the barrel extension, cutt forcing cone and lap it. But I often just use a fine file with safed edges (no teeth) instead. Usually I am working with a barrel I just fit. Once the cylinder will close I hold it up to a light and press the cylinder forward. Wearing an optivisor you can see if there is a spot that touches or use a thin feeler gauge and find the tight spot. Then hold the file with more pressure on side or top bottom. You can file perfectly flat. It is a mater of actually knowing how to use a file correctly.

I also took a set of feeler gauges from .002 to .010 and clamped them tightly together and took them to my belt grinder with a fine belt and made them only about 3/8 wide. Some sets will not pass though between the frame and gas ring on J and K frames. This set will and allows you to check for any difference between top and bottom gap.

I am going to fit a model 15 barrel on a J&G frame I installed adjustable rear sights on today. That will be J&G frame #5 that is now a functioning gun again. I have decided the last one will become a 6" 327 Federal

I like the way you think. .327 Federal Mag., what's not to like?

 

[cjtraining]

I bought two shims from an E-Bay vendor. I read the part on end shake shim installation in Jerry Kuhnhasuen's shop manual. With the information I received from forum members and the manual, I installed one shim and measured the b/c gap. The gap was .005 and no end shake or cylinder movement when cocked. With snap caps in the cylinder, I pulled the trigger about 100 times. There was no marring on the cylinder front. Is there anything else I need to do?

 

[murphydog]

Verify the contact issue is resolved with live ammo, polish the cylinder face and enjoy!

 

[stansdds]

As long as you have not induced a binding issue between the ratchet and recoil shield, then test firing is the final test.

 

[steelslaver]

I wouldn't surprise me that the barrels rear face was a tiny bit out of square. My narrowed set of feeler gauges has shown me that it isn't uncommon by a couple thousands. Plus just the other day I discovered a K frame 38 special cylinder that was .002 out of square, Drug on one half and not the other when I was fitting it.

 

[armorer951]

Sounds like you have successfully corrected the problem.

You could also verify that the rear gauge, or headspace is correct using your feeler gauges. The headspace should be .064" between the breechface and the rear of the cylinder. (+/- .002")