Ruger Forum

Sp101 Endshake

This is a discussion on Sp101 Endshake within the Ruger Double Action forums, part of the Pistol & Revolver Forum category; intercooler, Endshake is to revolvers what tread is to tires. When endshake starts approaching .005", it's time to take action before the frame and cylinder ...


Go Back   Ruger Forum > Pistol & Revolver Forum > Ruger Double Action

Reply
 
LinkBack Thread Tools Display Modes

Old October 8th, 2012, 01:33 PM   #16
Retired Gunsmith
 
Iowegan's Avatar
 
Join Date: Aug 2006
Location: Blair, NE
Posts: 8,966
Iowegan has a spectacular aura aboutIowegan has a spectacular aura aboutIowegan has a spectacular aura about

Awards Showcase

intercooler, Endshake is to revolvers what tread is to tires. When endshake starts approaching .005", it's time to take action before the frame and cylinder get damaged. Other known problem areas for all revolvers is the cylinder lock notches. If you pull the trigger too fast in DA or cock the hammer too fast in SA, the lock notches and cylinder latch will take a beating and eventually peen where the cylinder has too much side play. Another thing to check is "carry up" timing. This is done by slowly pulling the trigger in the DA mode. The cylinder should lock up before the hammer drops. This is a good wear indicator for the ratchets, pawl (hand), and hammer dog. No amount of lubrication will prevent peening, which is the mechanical action where two parts strike each other versus friction when two parts rub against each other.



Iowegan is offline  
Advertisements
Old October 9th, 2012, 06:47 AM   #17
 
Join Date: Mar 2012
Location: NJ
Posts: 873
TMan51 is on a distinguished road
Quote:
Originally Posted by intercooler View Post
Well this really sucks. I need to check my GP-100 then.
It's pretty expensive shooting a GP100 to the point of failure, most don't have the time, or the cost of the ammo.

I have a BH .357 with an easy 10K rounds through it, mostly cast loads at medium levels. It has no measurable wear on anything. But I was able to stress a nice M19 shooting thrill level loads with heavy bullets and lots of W296, took about 5 years at maybe 100-150 rds a month. Even then it was serviceable as a shooter, just loose. My K-38 saw far more action, a lot more, and was good as new when I sold it to a K-38 fan. Bad decision.

My question for KaTo was pure curiosity, as I will not shoot any max loads from my SP101, ever. It will get some jacketed stuff, moderate loads, but mostly cast/extruded lead also at moderate levels by .357 standards. If I really need power in a handgun, I'll bring my SBH to the game. I'm thinking if it will take 2K factory 158's, it will easily digest all of the stuff I feed it, and still be working when I leave for the next world. Taxed to death by Democrats.
TMan51 is offline  
Old October 9th, 2012, 10:31 AM   #18
 
Join Date: Dec 2011
Location: Iowa
Posts: 65
KaTo is on a distinguished road
If you do the math I have actually put over twice the cost of ammo through this gun than its original purchase price. Back when ammo was cheaper to boot. Not typical use by any means. I actually have moved to lead 38's primarily and with all the loose brass floating around have a nice stockpile for loading. I have since picked up a new sp101 with a b/c gap running between 0.007 max and 0.004 min factory fresh. I re-took the measurements of mine after getting all of the lead off and it is actually at 0.008 max and 0.002 min, quite a difference between the two. The difference in the wear items, pawl, transfer bar, and yoke, is also very noticeable and the triggers are like night and day. I called ruger and they say that since my hammer is fully functional and not related to the wear that they will take care of it, shipping and all. Go Ruger!

For educational purpose I took a picture of the end of the yoke tube on the new and old sp101, I'll let you figure out which has 2k on it.

I did notice that the carry up timing of my new sp101 is solid for four cylinders and quite a bit slower on on, still reaching full lock up as the hammer drops. I know that pawls are available as it is not a "factory fitted part" and I am wondering if they are also available as oversize? I can find over sized pawls for the single action while DA seems to have none.
Attached Images
File Type: jpg IMGP0640.JPG (659.9 KB, 40 views)

Last edited by KaTo; October 10th, 2012 at 05:39 PM.
KaTo is offline  
Old October 10th, 2012, 05:54 PM   #19
 
harrydog's Avatar
 
Join Date: Mar 2010
Location: Ohio
Posts: 109
harrydog is on a distinguished road
Quote:
Originally Posted by Iowegan View Post
Endshake is fore and aft cylinder movement when the cylinder is locked into the frame. The way to measure it is to use an automotive type gap gauge (feeler gauge) and measure the barrel-to-cylinder gap (B/C gap) by first wedging the cylinder fully forward. Measure the B/C gap again with the cylinder wedged fully to the rear. Endshake will be the difference between the two measurements. For a SP-101, you want about .002" but not more than .005". If endshake is too tight, the cylinder will bind up. If it is excessive, several conditions could result including misfires from light primer hits, cylinder unlatching when fired (very dangerous), cylinder dragging on the barrel, etc.

Endshake comes from four sources ... the end of the crane tube (S&W calls it a yoke tube) will peen and get shorter. A channel will get cut inside the cylinder's center hole, which is the mating surface for the crane tube. This causes the crane tube to seat deeper. The other two areas are the end of the ratchet column and the recoil shield where the ratchet column mates. Generally, all four surfaces will peen and increase endshake. Short of replacing the frame and/or cylinder, there's nothing you can do about excessive endshake if if comes from the recoil shield or the ratchet column.

How can you determine the source of the problem? If the cylinder moves too far rearward where the B/C gap exceeds .008" (.004"~.008 is normal, .006" is optimum), either the ratchet column has peened shorter or there is a depression in the recoil shield. You can usually see or feel a depression in the recoil shield. If the ratchet column is peened, the normally sharp edges will show evidence when compared to a new gun.

Based on the measurements posted by KaTo, it appears the B/C gap is wider than normal, which indicates a couple thousandths peening at the rear ... ratchet column, recoil shield, or both. The only fix is to replace the cylinder and/or frame but because the B/C gap is still in spec (barely) repair would not be necessary.

The worst issue is when the B/C gap is way too tight with the cylinder pushed forward ... almost causing the cylinder to scrape on the barrel. This can be repaired by installing "endshake bearings", which are nothing more than very thin washers. Before installing endshake bearings, two very important issues must be resolved. The first requires a "facing cutter" tool that removes a few thousandths from the end of the crane tube, removes the peened area, and squares up the end of the tube so it will mate properly with the bearing surface inside the cylinder's center hole. The inner hole mating surface must be dressed smooth and straight to eliminate the channel that was cut by the crane tube. The tool used to do this is a cylinder shaped grinder bit. I buy the ones with a 1/4" shaft and a 1/2" abrasive cylinder then use a shaping stone to size the diameter so it will just fit in the gun's cylinder center hole. After shaping the outside diameter, I use epoxy on the circumference of the body of the grinder bit so it won't damage or enlarge the diameter of the cylinder's center hole. This leaves a flat abrasive tip on the grinder bit so you can chuck the bit in a variable speed drill and hone the inside mating surface, typically removing about .005".

With the crane tube cut shorter and the inside cylinder hole deeper, it will increase endshake by several thousandths. No problem ... just stack endshake bearings until endshake measurements are within spec ... closer to .002" is best. Brownell's sells endshake bearings (made by Power Custom) in .002" thickness ... pack of 10 for about $20.

After endshake bearing are installed properly and endshake is well in spec, the gun will actually hold up better than when brand new. As noted above ... 357 Mag ammo takes its toll so it's much wiser to shoot 38 Specials for practice and run a cylinder or two of Mags now and then just for grins. If endshake is allowed to get out of control (more than .005"), it will allow enough fore and aft motion to "jackhammer" endshake much faster. At some point, the cylinder latch will release when fired and could result in a dangerous situation.
Would this also apply to the GP100?
harrydog is offline  
Old October 10th, 2012, 09:17 PM   #20
Retired Gunsmith
 
Iowegan's Avatar
 
Join Date: Aug 2006
Location: Blair, NE
Posts: 8,966
Iowegan has a spectacular aura aboutIowegan has a spectacular aura aboutIowegan has a spectacular aura about

Awards Showcase

KaTo, Based on the shape of the left crane tube, I would highly recommend sending your SP-101 back to Ruger or putting it in retirement status. That nasty angle on the end of the crane tube has no doubt cut a deep channel in the cylinder's center hole. By the time you get the crane tube dressed back and the channel in the cylinder taken care of, the crane tube is going to be too short for endshake bearings. Most likely, Ruger will replace the cylinder and crane, which should restore the gun back to good operating condition.

harrydog, Ruger doesn't share their specifications with the public so the numbers I quoted were general specifications that apply to most all DA revolvers, no matter what brand. GP-100s have a stronger crane tube than a SP-101 but if enough magnum ammo has been fired, it will eventually peen just like Kato's SP-101. The same goes for Securty-Sixes, Redhawks, and Super Redhawks. S&W revolvers have a much thinner yoke (AKA crane) tube so they will suffer from endshake far sooner than any Ruger. That said, a standard K-frame 38 Special S&W will last 30,000~40,000 rounds before endshake become an issue. The same basic K-frame 357 Mag firing 357 Mag ammo probably won't last more than a couple thousand rounds before it needs endshake bearings.

When people buy the large frame S&Ws and Rugers ... specifically a S&W Mod 27 or 28, or a Ruger 357 Mag Redhawk, they think they are getting the strongest guns money can buy because the cylinders are so thick. These revolvers were designed for 44 cal but chambered for much smaller 357 Mag cartridges, which makes the cylinders very heavy. When endshake allows a little fore/aft movement, these heavy cylinders develop a lot of momentum, act like a battering ram, and beat the yoke/crane tube to death. Further, the massive cylinders also beat the lock notches to death when the revolvers are operated in a normal manner. A combination of peened lock notches and excessive endshake is an accident waiting to happen. Likely, this is the reason why Ruger quit making the Redhawk in 357 Mag.

Here's why excessive endshake is so important .... If you look at the top area of a cylinder latch and the lock notches in the cylinder, you will note they are crescent shaped. When a revolver is well within spec, the crescent cylinder latch locks into the cylinder's crescent lock notches and holds the cylinder horizontally where the chambers align with the bore. The only thing that holds the cylinder latch in position is a little coil spring. When endshake is normal, the cylinder can't move forward far enough to dislodge the latch; however, when the cylinder develops enough forward endshake movement due to peening like Kato's left photo, the rounded cylinder latch will cam down when the revolver is fired and release the cylinder. This can be a very dangerous condition because the bullet exiting the cylinder throats could strike the side of the barrel instead of being directed into the forcing cone. Besides totally ruining the gun, it could also present a serious danger to the shooter.
Iowegan is offline  
Old October 11th, 2012, 05:04 AM   #21
 
Join Date: Mar 2012
Location: NJ
Posts: 873
TMan51 is on a distinguished road
Quote:
Originally Posted by Iowegan View Post
That said, a standard K-frame 38 Special S&W will last 30,000~40,000 rounds before endshake become an issue.
That explains why my K-38 seemed indestructable. I went through a truck load of Speer and Remington WC's over 3.8gr of Red Dot, and if it ever loosened up, I wasn't able to find it.

Learned a lot about wear and end shake on this thread though.

I'm guessing my SP101 will last a while as my favorite load in that is 6gr of W231 and a 160gr cast. It's pretty easy to unload a hundred rds.
TMan51 is offline  
Old October 11th, 2012, 05:41 AM   #22
 
Join Date: Dec 2011
Location: Iowa
Posts: 65
KaTo is on a distinguished road
I am in 100% agreement on a trip back to Ruger. I estimated that to completely remove the peened area both the crane and cylinder would need to be cut back about 0.018" which seems like far to much material from such a critical high pressure area. After it gets back from Ruger I am going to rinse and repeat with 38 special and see how she handles that 20k mark.
KaTo is offline  
Reply

  Ruger Forum > Pistol & Revolver Forum > Ruger Double Action



Search tags for this page
crane yoke fit on ruger sp101
,
cylinder & slide custom ruger
,

end shake

,
endshake
,
revolver end shake
,
revolver endshake
,
ruger revolver cylinder end shake
,
ruger revolver endshake
,
ruger sp101 endshake
,

sp101 endshake

,
sp101 endshake spec
,
sp101 excessive endshake
Click on a term to search for related topics.

Thread Tools
Display Modes


Similar Ruger Forum Discussions
Thread Thread Starter Forum Replies Last Post
Endshake....101 ScottMn Ruger Double Action 9 July 30th, 2012 05:37 AM
SP101 Endshake Bearings Ridgeline Gunsmithing 0 August 6th, 2011 04:24 AM
sp101 endshake wrv Gunsmithing 3 October 22nd, 2009 04:40 PM
B/C gap = endshake G. Freeman Gunsmithing 1 September 29th, 2009 09:51 PM
Endshake Bearing? Longlosthiker Ruger Double Action 3 May 8th, 2009 10:50 AM

Top Gun Sites Top Sites List  
Powered by vBulletin 3.8.7
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.1
Copyright © 2006 - 2014 Ruger Forum. All rights reserved.
Ruger Forum is a Ruger Firearms enthusiast's forum, but it is in no way affiliated with, nor does it represent Sturm Ruger & Company Inc. of Southport, CT.