David Bradshaw Photos Vol. 109 - S&W Cylinder Pin

[Lee Martin]

To smoothly unlock and open S&W cylinder requires correct CYLINDER PIN. Model 29 .44 Mag, above, shows cylinder pin as a connecting rod between THUMBPIECE and lug under barrel which centers EJECTOR ROD when cylinder is closed. Ejector rod (shown resting on yoke cut in frame) attaches to ejector via left hand thread.


Cylinder pin in breech face of S&W M-29. Hollywood gun handling, macho flipping cylinder into frame, eventually egg-shapes pin hole. Causing sloppy alignment and more hammering of the cylinder stop. Years of normal operation also causes eventual looseness. Lubrication keeps steel happy, reduces wear. It is unusual for the center pin to wear on the breech end.

Cylinder pin spring-loads into breech face to provide cylinder lockup of S&W design. If hole in breech face becomes egg-shaped from abuse, excess play develops (Hollywood syndrome). Some play develops in magnums over years of shooting; since steel likes lubrication, oil or grease slows process.


Spring-loaded stud, or latch below barrel performs two functions: 1) stud secures cylinder pin in standing breech (breech face), and 2) centers ejector rod. Thus, cylinder is held in frame by pin @ rear and ejector rod @ front.


Insert empty brass into chambers before loosening or tightening EJECTOR ROD. Ejector rod threads directly into ejector with left hand threads. Pad knurled end of ejector rod to prevent damage from plier. Tighten ejector rod just a bit more than finger tight.


Shots fired X recoil hammers forward end of CYLINDER PIN. Recoil----primarily of .44 Mag----acts to peen cylinder pin against spring-loaded stud in ejector shroud. First symptom may show as difficult cylinder opening, as shortened pin fails to release stud from ejector rod. (Difficult opening may also indicate loose ejector rod.)


Forward end of cylinder pin, peened by stud under barrel. Swelling from .130-inch rod to .136" prevents removal of cylinder pin spring. Peened pin binds so tight in ejector rod, thumbpiece cannot be pressed forward to open cylinder. M-29 4" was stripped from the inside to remove cylinder. Light touch on belt sander cleans up swollen end of cylinder oin.

Side effect, cylinder pin jammed in ejector rod: SA and especially double action pull feels like worn cylinder stop. A worn cylinder stops disengages & re-engages before start of cylinder rotation.


With thumbpiece pressed forward, cylinder pin protrudes beyond ejector rod. Generous protrusion shown. If cylinder pin is too short, attempt to open cylinder hangs on stud (under barrel). Knurled end of ejector rod may be filed to shorten. Be sure to bevel exterior end of ejector rod----to slip over stud when closing cylinder. A very light chamfer inside ejector rod eases opening.


Bottom sketch shows short cylinder pin. Or, loose ejector rod. Sketch does not show desired chamfer in end of ejector rod.


-Lee
www.singleactions.com
"Chasing perfection five shots at a time"

[bradshaw]

Side effect, cylinder pin jammed in ejector rod: SA and especially double action pull feels like worn cylinder stop. A worn cylinder stop disengages & re-engages before cylinder rotates.


David Bradshaw

*****

Note burnished edge of swollen CYLINDER PIN. Under .44 Magnum recoil, inertia of the spring-loaded cylinder pin causes it to act as a miniature slide hammer against the stud which enters the EJECTOR ROD. This rod is overdue for service, as plastic deformation caused the pin to stick in the ejector rod. The burnished edge reflects binding of pin in ejector rod. The THUMBPIECE won’t budge. Single action cocking feels about normal. Trigger sticks hard at beginning of double action pull, as it feels as though the cylinder stop won’t release the cylinder to rotate. The difference: a worn or poorly tuned cylinder stop doesn’t release cylinder.
David Bradshaw

[bradshaw]

A shooter asked why the CENTER PIN plays a part in the tune of a Smith & Wesson. Stoned the flare on the peened end of center pin, did not include photo. Trust Vol. 109 helps explain....
David Bradshaw

[jfs]

Dave, Once ordered and fit a new cylinder pin, that was oversized, to a K frame.... It was a matter of file the end of the pin, reassemble cylinder assembly and check the fit and repeat until it looked like the top sketch in your notebook.... Still works fine after all  these years....

[jgt]

I was watching a documentary about the Air Force paramedic training. One of the instructors was sitting on the tailgate of a pickup and loading a six-inch 357. When the cylinder was full he did the hollywood flip to close the cylinder. That is the moment I knew he was full of ..... well you know what he was full of.
I have purchased several Smith & Wesson revolvers over the years with the problem discussed here. I came by them at a real bargain.
I also learned when showing at a gun show to cock the hammer on Smith & Wesson revolvers and put a ty-rap around the hammer before lowering it. That would make it impossible for tire kickers to open the cylinder unless the ty-rap was removed. I didn't mind doing it for those interested, but it kept the couch cowboys from trying to impress their girl friend with their spinning the cylinder while flipping the crane closed. It would help if directors would cut that little trick out of their movie scripts, but fat chance of that happening until they stop using revolvers all together. Until then, Brownell's sells the proper tools made to perform the job mentioned here.

[weiler]

My 629-3 4” has been in the house for a couple years now and has had a slight “gritty” feel when pressing the cylinder release. Took the cylinder assembly apart as described and while the cylinder pin looked fine, a micrometer showed the end was flared about 1 thousandth, cleaned it up with a fine stone and paper and she runs much much smoother. Thanks David!