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Discussion Starter · #1 ·
I just came into a S&W Model 10, serial # dates it from 1985.

It has a very small amount of - what I understand to be - end shake. Very small, but definite. If the movement were any less, it would be imperceptable. That said, it is there. There is nothing that is free or loose feeling. I move the cylinder in the direction of the firing pin. When released, it returns.

I have a Model 27 and 29 that have pretty much zero end shake, but the Model 10 only fires 38 Specials, so thought my gun may have passed quality control because 38's wouldn't cause a long-term issue on the K frame Model 10. Or maybe my 27 and 29 are better than average.

BTW, I only recently came to learn about end shake, and this gun was the first I tested it on (I then checked the 27 and 29). So, I don't have any gauge on what may be called acceptable.

I know this is kind of a 'blind taste test' haha, but eager to hear your thoughts.

Thanks in advance!
 

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A tiny amount of endshake is not a problem. Even your other S&Ws have some - even if it is so slight as to be imperceptible. There has to be some play or else the cylinder will bind up when it gets warm from shooting.
Unless and until it gets to be more than a few thousandths of an inch it is still in spec and nothing to be concerned about.
 

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Can you measure the cylinder-to-forcing cone gap? (Of course, with the gun clean). It should have .003" minimum, and if it gets to .006" or .007" you are heading toward problem country.
 
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Discussion Starter · #5 ·
Thanks so much - I had heard about the shims so thought any fix that might be needed wouldn't be difficult to take care of. It did seem to me that I probably didn't have a problem on my hands, per se, but as the end shake is something I'm new to I wanted to ask. Thanks!
 

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Discussion Starter · #6 · (Edited)
Can you measure the cylinder-to-forcing cone gap? (Of course, with the gun clean). It should have .003" minimum, and if it gets to .006" or .007" you are heading toward problem country.
Unfortunately, I don't have what I need to do that (measuring shims, I'm guessing). Should probably be next on my to-buy list. However, I can definitely say that the gap is smaller on the 10-7 than it is on my 27 and 29, both of which are pretty new. I need a light in order to see the gap in the 10-7.

FWIW, the 10-7 also likely has a very low round count.
 

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Unfortunately, I don't have what I need to do that (measuring shims, I'm guessing). Should probably be next on my to-buy list.
Go to your local Harbor Freight buy a blade-type feeler gauge like this one.
Simple tool and only costs a few bucks.
Composite material Electric blue Temperature Font
 

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Don't know if you've seen this video or not, but it does a good job of describing endshake on a Smith and how to fix it.
Wow, thanks for that video. I've been following this thread but I had no idea what "end shake" was. That video explained it perfectly, except I don't think he mentioned what was acceptable. His example had a revolver with .010 end shake and he put in a .004 and .002 bearing so I guess something around .004 is acceptable?
 

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.004 is maxed out IMO. The revolver still has .010 worth of barrel cylinder gap in that vid. Wow, that's nothing I would own. They can now use that gun to show how to turn back the barrel to fix that. One note worth mentioning is 3-4 thousandths end shake is fine on centerfire and even more than that will not cause any running issues in general but, put that in a rim fire and you most definitely want to hold to .002-.003 especially if you have the trigger tuned for light trigger pulls. Rim fires with loose end shake will most likely have light hit problems (fail to fire).
 

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Ask 10 armorers and you'll get 10 different answers. From what I've read, seems like a cylinder-to-forcing cone gap of .003" to .006" is acceptable -- anything over .008" is considered too much on a S&W center fire revolver.
But I certainly don't have any personal knowledge of what's correct.
 

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Discussion Starter · #13 ·
Got a feeler gauge and went to work measuring (thanks again for the tip!)...then came to the forum and watched that video, haha.

I had first measured the gap while holding the gun from the handle, not touching the cylinder. After watching the video I measured the gap while holding the cylinder back. Here are the results:

S&W 10-7
  • neutral, the gap (cylinder to forcing cone) was .003
  • cylinder pulled back, the gap was .007

Model 27
  • neutral was .008
  • couldn't pull the cylinder back even one little bit

Model 29
  • neutral was .006
  • pulled back was .008

Watching the vid, I believe I have misunderstood end shake, confusing it with simple gap width between forcing cone and cylinder.

Sounds like end shake is calculated by finding the difference between neutral and pulled back positions. In my case, that would be end shakes of .004, zero, and .002
 

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Close. I would describe (and measure) endshake as the difference between the cylinder pushed forward and the cylinder pulled back. Here is the answer. ^ ^ ^ ^ BC605

In other words, It is the total amount of travel of the cylinder from front to back.

*



FWIW, the average sheet of computer copy paper is a bout .003".
 
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Just to needle dick this a little further, Measure, record, rotate cylinders 2 chambers over, repeat, rotate over 2, repeat. Compare your notes. Dont be surprised if you get a .001 hick up in the numbers. Its no absolute guarantee the cylinders are dead center on their axis. This is one test that Gunsmiths perform just to see why some revolvers are throwing flyers. It may be miniscule, but it all adds up with other irregularities.
 
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