Cylinder End Shake

[Sequins]

Hello friends,

I just recently sent my Ruger SP101 to the factory to resolve an issue with the pawl and I just received it today. They included a statement of work that indicated the pawl and hand repairs I had needed, but they also mentioned they adjusted the "cylinder end shake".

I was surprised that was something Ruger handled unprompted as I hadn't even realized that was an issue with my gun. I've fired hundreds of rounds through it with no issue until I had the pawl/hand issue that I sent it in for.

I did some googling and I'm not satisfied that I really understand what cylinder end shake is. I'm doing some more research on the interwebs but I thought I'd ask you all as well: What is cylinder end shake, how is it adjusted, and how is it avoided?

[Deaf Smith]

End-shake is when the cylinder moves forward and aft with the cylinder closed. If to much end-shake then the paw might not engage the ratchet on the cylinder to rotate the cylinder.

Deaf

[45 Dragoon]

End shake is the forward/rearward movement of the cylinder. If there is any or more than minimum spec., shims can be installed between the cylinder and the removable bushing (as in Colt S.A.A.s and copies of) or the front of the bushing can be "upset" to lengthen it and then re-fitted. In the case of your Ruger, they probably replaced the pressed-in bushing and re-fitted it.

Mike
www.goonsgunworks.com
Follow me on Instagram @ goonsgunworks

[tipoc]

I check cylinder end shake with an unloaded revolver. I drop the hammer on an empty chamber and hold the trigger back. Then, with the trigger back, check the amount of movement of the cylinder left to right (side to side). On S&Ws and Ruger the movement will be only a few thousand each way. Move the cylinder front to rear, it should be within .006 usually. This can be checked with shim as well or what used to be called a spark plug gage.

I'm not sure where you can find the actual acceptable tolerances for your gun. That might be in Jerry Kuhnhausen's book on the Ruger revolvers. Others may know more.

tipoc

[Sequins]

Thanks for the excellent information gents, this is exactly what I wanted to know!

[Carmady]

Instead of repairing my LCR, Ruger replaced it with a new LCR, which I discovered had .005" end-shake.

Called Ruger and was told .005" end-shake was within their specs.

I asked how much end-shake it took to be out of spec, and was told that that wasn't public information.

[tipoc]

I don't know about the LCR in particular. You can probably ask a local gunsmith about that. I think it will likely be about what is standard for for other revolvers. Usually it's between .03 to .006 and may get a bit larger with use by a couple of thousand.

You may be able to find out more over to the Ruger forum, they have a gunsmithing section there. Or you can check in that same section here.

tipoc

[Carmady]

Usually it's between .03 to .006 and may get a bit larger with use by a couple of thousand.

Was that meant to be .003 instead of .03? If so, it sounds like you might be talking about barrel-to-cylinder gap.

[tipoc]

Yep, barrel to cylinder gap. I think that's what the op is asking about. Did you think it was something else? Cylinder to breech gap? looks like Ruger did not indicate which it was. I assumed cylinder to barrel gap. Could be the other...

tipoc

[Carmady]

Did you think it was something else?

It's my understanding that end-shake is a separate measurement from b/c gap. B/c gap is what you have when the cylinder is locked/still, the cylinder won't move much fore and aft. If you measure the b/c gap with the cylinder pushed forward, and then measure it with the cylinder pushed rearward, the measurements will be about the same IF there isn't any end-shake. There needs to be a little end-shake so the parts can move.

Excessive end-shake, like .005", will be enough to be felt as slop on the cylinder. You'll also likely get different b/c gap measurements when the cylinder is pushed fore and aft. You could have a b/c gap of .006" with the cylinder forward, and .011" (.006" b/c gap + .005" end-shake) when the cylinder is held to the rear.

That's how my LCR was.

[tipoc]

I may be simple minded, or just simple. Or taught wrong. But...

Once you've decided there is reason to test it, which is after brief gun handling observation suggests it may be a good idea. B/C gap is best tested with the cylinder all the way forward. First clean off any powder residue/build up on the rear of the barrel and from the front of the cylinder. With an empty gun, pull the trigger, which drops the hammer, do not release the trigger, and hold it to the rear. In a S&W, the cylinder will be as far forward as it's gonna get. Now check with feeler gauges. Anywhere from .003" -.006" is about normal and like I said earlier it will get a bit more than that with usage. Check each chamber in the same manner.

You don't really have to do much more than that to give a quick test. But from that point on if something looks odd you can go further. I'm sure others will come forward with suggestions on that.

Ruger could have been referring to a few issues other than simple the b/c gap being a bit off.

tipoc

[45 Dragoon]

Barrel/cyl gap is exactly that. The "gap" is what is created by the gas ring or "bushing" which holds the cylinder from contacting the rear most end of the barrel.
End shake is the overall for/aft movement of the cylinder along the base pin.

In the case of an open top revolver, such as an Army, Navy, Walker, Dragoon, . . . , there is no bushing/gas ring and it is normal for the face of the cyl to contact the barrel assy. Therefore, you have a barrel/cylinder clearance. That clearance, by the way, is determined by the length of the arbor, not how far the wedge is inserted.

Mike
www.goonsgunworks.com
Follow me on Instagram @ goonsgunworks

[tangolima]

When end shake is more than 0.004", I will work on the revolver to reduce it to less than 0.002”.

End shake is end shake, different from cylinder gap or head clearance.

-TL

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[Hawg]

B/C gap is best tested with the cylinder all the way forward.

tipoc, the subject isn't cylinder gap, it's end shake. Two entirely different things.

[tipoc]

OK. Got it!

tipoc

[Dfariswheel]

Here's the correct way to check ACTUAL cylinder end shake......

With the gun empty, push the cylinder to the rear and HOLD it there while you use an automotive feeler gage set to gage the gap between the rear of the barrel and the front of the cylinder.
(Note: This is also the ACTUAL barrel-cylinder gap).

Then, push the cylinder forward and hold it there while you gage the barrel-cylinder gap again.
(This is NOT the true barrel-cylinder gap. This gap is the cylinder sliding forward. When end shake is correct the cylinder is held to the rear, and that's the real barrel-cylinder gap).

Subtract the one measurement from the other and that's how much end shake the gun has.

Different brands have different specifications on how much end shake is acceptable.
As example, Colt DA revolvers specs allowed no more then 0.003".

S&W is a lot looser. Anything over "about" 0.006" OR when the front of the cylinder is contacting the rear of the barrel requires repair.

I don't know what Ruger's spec is, but they will be listed in the Jerry Kuhnhausen Shop Manuals on the Ruger revolvers.

Note that cocking the action or holding the trigger back will give a false indication of actual cylinder end shake.
This might make the end shake seem less, but when fired the recoil impulse will force the cylinder forward and backward, which is the actual end shake.

Excessive cylinder end shake is bad news because if the cylinder can slide back and forth, the mass of the cylinder slamming back and forth under recoil will literally hammer the frame, cylinder, and ejector to death.
In a gun that's continued to be used after the limit is reached you see serious battering damage of the cylinder, ejector, and ejector ratchet impact peening on the frames breech face.

Repair also varies from maker to maker.
On the S&W repair can be to stretch the cylinder yoke barrel by several methods, or by dropping in greased stainless steel bearing washers to tighten the fit.

Colt's are unfortunately much harder to repair.
You cannot install bearing washers in a Colt because that would destroy the cylinder and damage the frame.
In the Colt's you have to find a Master pistolsmith like Frank Glenn in Arizona who has a special hydraulic device used to stretch the collar on the front of the cylinder.

Bottom line, excess cylinder end shake is a gun-killer if left uncorrected.

[jmstr]

a while ago I got some numbers from Ruger regarding 'within spec' endshake numbers. This was for the Blackhawk, but I would think it should be the same spec for all .357 revolvers.

the range of acceptable was .002-.011". that said, anything over .009" was something that may or may not be adjusted- depending on other wear points.

I sent in my blackhawk and they fitted the barrel/cylinder properly to remove endshake, and now it is around .004".

If you have under .002, you might get cylinder binding as things get hot and lead/powder begins to deposit on cylinder face.

Just some info to think of.

[tangolima]

0.002 - 0.011” acceptable? I am surely too old to fit in this new age. Endshake of less than 0.002" doesn't cause binding, I don't think. An revolver is not AK. Sloppiness doesn't make it better.

Just some food for thought, does semi auto have something equivalent to endshake in revolver?

-TL

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