GP100 Endshake and cylinder play questions.

[FullEffect1911]

Hello,

I have a few questions about my gp100. First the gun shoot great and isn’t spiting out of the barrel cylinder gap as far as I know.

But there is a slight end shake condition of .003” to .006” from measuring on the B/C gap with feeler gages. From reading the revolver checkout thread and learning more about revolvers I believe that even though some people say Rugers can handle some end shake, I just can’t see how this is a good condition to have. So I would like to purchase some end shake bearings from Midwayusa (they have them for the GP) and fix the problem myself. A .002” end shake bearing should give me a B/C gap of about .005”-.006”.

What is the procedure for installing these bearings once the cylinder is off the firearm? Is there other tools I will need in order to do the job right?

Also as a point of confusion on my part I have a question about revolver checkout. With the gun is EMPTY, full lockup, looking down the barrel and shining a light to check for proper timing. Do you allow the cylinder to remain at rest or do you try and use the rotational play to get it out of alignment? I would assume that you would check this while the cylinder is at rest as it would be at the point of firing, but I would like to just make sure.

I look forward to any insight on these topics.
FE1911

 

[dfariswheel]

Except for the older Colt action like the Python, Detective Special, etc. all modern DA revolvers are specifically designed to ALLOW the cylinder to be slightly loose at the moment the hammer drops.

The purpose of this is to allow the bullet passing from the chamber to the barrel to force the chamber into alignment with the bore.

The older Colt actions are the only one that forces the chamber into perfect alignment with the bore, then LOCKS it there. This is Colt's famous "Bank Vault" lock up.
The reason this is not used on designs by S&W and Ruger is because the action is cheaper and easier to build, and requires little hand fitting and adjusting versus the Colt action that is a totally hand assembled, fitted, and adjusted action that cost significantly more to build.

So, your Ruger, (and S&W, Taurus, Dan Wesson etc) MUST be slightly loose to operate properly.

 

[easyrider604]

all modern DA revolvers are specifically designed to ALLOW the cylinder to be slightly loose at the moment the hammer drops.

My GP100 locks up tight...the cylinder feels like it is welded to the frame.
So this is bad?

One 686 cylinder rotates, just barely feel it move, not enough to measure.
The other 686 has an estimated .5 mm (measured at the circumference) free play at lock-up, same as the Blackhawk. Good or bad? How much play is
acceptable?

 

[GP100man]

i totally agree with dfariswheel!!
when i was younger & had more $$ & time i shot colts & once a yr to colt they would go for retiming to stop spittin .
i`ve got all rugers now & i have 1 6" GP that just is a naturally good pointer ( i doubt it`s any better than the others ) but this revolver has a recorded 6,200 rnds through it & it measures the same now as the day i bought it!!!!!


GP100man

 

[dfariswheel]

Even though some revolvers can seem to be locked very tightly, when fired there's enough "give" built in to the action to get the job done.

There is no standard as to how loose the cylinder can be, although excessive looseness (a pistolsmith's judgment call) is often a sign of a worn action.

 

[machinisttx]

Some of my guns have more end shake than that, and I can't say that it bothers me. Any revolver is going to have some play in it, but what you're describing isn't excessive or cause for concern.

Dferriswheel knows his business on revolvers.

 

[FullEffect1911]

Well that's good then, I didn't want to spend 20 or so bucks on the endshake bearings if I could avoid it.

The description Jim March gave of the cylinder acting as a battering ram every time the gun is fired gave me some pretty destructive images in my head about what is happening to a revolver with end shake.

But I am sufficiently convinced that modern revos can live with it.

Thanks.

 

[Old Fuff]

Observations on rotational play.

Many years ago I had an interesting discussion about rotational play with Bill Ruger. They had received a contract for Security Six revolvers from one of the U.S. military services, but the contract specified that there be a tighter fit between the cylinder notches and the cylinder latch then was factory standard. He observed out loud that in his opinion this extra tight fit could result in malfunctions if the notches accumulated a small amount of fouling or dirt. I replied that in my experience the folks that made the drawings and specifications often didn’t understand zip about firearms, and it wasn’t unusual to find unreasonable dimensions or tolerances. In one instance I knew of there was a +/- .003” tolerance on a part where nothing touched it! A +/- tolerance of .125” wouldn’t have made any difference in the way the part worked in the gun.

Colt owners might notice that the cylinders in their revolvers do not lock absolutely tight except when the trigger is pulled and held all of the way back. This is because the hand is rotating the cylinder so that the ball on the cylinder bolt is pushing against one side (and only one side) of the cylinder’s notch. This may seem great, but only if the chamber is concentric with the bore. This was usually true back when Colt could use what amounted to unlimited skilled hand labor to individually fit up each revolver. Later when they couldn’t the expectation of getting perfect alignment became less and less. When they went to a newer design starting in the 1970’s the cylinders were locked in the same manner as Smith & Wesson’s and Ruger’s, yet accuracy didn’t seem to suffer.

 

[FullEffect1911]

Thank you for information Old fuff.

I was actually reading on the Ruger forum about the play in ruger cylinders. One of the very knowledgeable members (seemed so anyway), mentioned that a tight cylinder in the rotational direction could actually be a bad thing. The rotational clearances allow the bullet to force the cylinder and bore into perfect alignment as the bullet travels down the bore. If the cylinder was rock solid, a absolute perfect cylinder to bore alignment would be crucial in order to have best accuracy and go without spitting.

I can believe that, especially since so few things are in perfect alignment with firearms... especially if the gun didn't cost what a freedom arms does.

The other thing was about vertical play/clearance in order to avoid the same problems as the rotational play.

And the last thing was that rugers perform best with between .002" and .005" of endshake. The reasoning for this is that the ruger needs that bit of endshake to prevent the cylinder from binding.

Apparently Ruger revolvers just work a bit different then smiths as far as what tolerances and clearances are concerned. And that isn't so surprising.

Here is the link... the individual that gave this information is Iowegan.
http://www.rugerforum.com/phpBB/viewtopic.php?t=5709&highlight=endshake

 

[Orange_Magnum]

Timing should be checked with the hammer fully cocked, cylinder untouched by your other hand. If the cylinder doesn't rotate eough, bend the hand that pokes the cylinder, and if that doesn't work, also sand deep valley of the frame so that the head of the swinging arm can rest deeper. If the cylinder over rotates, sand the tip of the hand or bend it the other way.