How much endshake?

[Jim NNN]

I always thought you didn't want any endshake (front to back movement) in a S&W revolver. As with everything else, a slight amount is fine.

My 681 L frame has what seems like a lot of endshake to me. I watched Larry Potterfield's video on fixing endshake, and - per his instructions - I measured the front to back movement with a feeler gauge. With the cylinder all the way to the back, the cylinder gap is .009, roughly. With the cylinder to the front, the cylinder gap is .005, roughly.

According to Mr. Potterfield, this means I have .004" endshake. He doesn't say what amount is acceptable. His demo gun has .010", which he says is too much.

What amount is acceptable, or should I try to get rid of all of it? I've already bought the endshake bearings from Midway (.002 and .004) but don't want to put them in if it isn't necessary or recommended. To my surprise, he has a remedy for addressing too little endshake, as well.

Thanks.

 

[OKFC05]

I like a little endshake for smooth running in long matches when the gun gets hot, say a thousandth or 2. Sounds like putting a .002 in yours would suit me, and it is easy enough if you know how to unscrew the ejector rod.

 

[Jim NNN]

Thanks for such a rapid response, my friend. That helps me a lot.

 

[Jim NNN]

Okay, just performed the operation, and everything went smoothly and the results are fantastic! Feels a lot more solid than it did before. Again thanks to OKFC05 for the advice and to Larry Potterfield at Midway for producing the video.

 

[Hapworth]

Kuhnhausen states endshake should be corrected once it starts to reach beyond .006". He recommends correcting to .001".

If you're going to fire magnum loads, I think endshake should be corrected sooner because of the greater stresses from the magnum rounds; endshake only increases with use, especially with the boomers.

I'd say you did right correcting at .004".

You want that .001" endshake dialed in as part of the correction to account for any slight tolerance variations and avoid stacking tolerances that might bind the revolver; also, to account for thermal expansion under fire to, again, avoid binding.

You're fine with .002".

If this is a defense gun, run it at the range and confirm proper function before returning it to the defense line up. Any change to your firearm requires this check. At minimum, check your headspace and dry fire empties or snap caps.

I once corrected endshake in a functioning revolver I'd fired hundreds of times. After proper endshake correction and confirmation of adequate headspace, I took it to the range and it bound up under fire. Turned out there were miniscule burrs on the blast plate that the cylinder was clearing only because of the excessive endshake, but bound the action once the endshake was corrected, and had to be filed down.

If I'd needed that piece and hadn't checked first after making a small change that passed ordinary inspections, it would have been bad.

Make a change, hit the range.

 

[Jim NNN]

Thanks Hapworth. Great advice. It isn't a defensive gun right now, but I like all my guns to be ready, so I'll take it out to give it a try.

I haven't taken a feeler gauge to it post repair, but it feels to me like it's more at .001" than .002" now, which is interesting because I put a .002 bearing in it and the pre-repair endshake was .004" - but as I said in my original post, that was sort of rough measurement with the feeler gauge. Right now it feels really solid with only an ever so slight movement front to back.

I'll try a half box of .38's and a half box of .357's and see how it works.