Wednesday, September 29, 2010

Gunsmithing the Revolver

Now I’ll be the first to tell you I am not a gunsmith. On the other hand, I’ve spent quite some time as a mechanism designer, and if the hand of man put it together, the hand of Billll can take it apart, re-assemble it, and reasonably expect it to work. The mind of Billll can even, eventually, figure out what the leftover parts were supposed to do, and tell you if they were really needed.

Earlier, at a club pin shoot, I got some comments about the amount of stuff spraying from the sides of my gun. Now revolvers do this normally, because of the gap between the cylinder and the barrel which allows the cylinder to turn freely. Never mind that the Russians came up with a way to make the cylinder move forward to eliminate this. Look, no side spray, and you can even mount a suppressor on the revolver, but what do those dumb Russkies know anyway?

There are two causes for excessive side spray: One is that the barrel is not as close to the cylinder as it should be. The fix involves modifying the barrel, and I don’t want to get in to that. The other reason is because the cylinder isn’t lining up with the barrel when the hammer comes down, which is a mechanism problem. The thing is that the cylinders seldom line up exactly right anyway, which is why the barrel starts out with a conical inlet at the cylinder end.

I noticed that the cylinder on my gun had rather more rotational free play in it than I thought it should have, and set out to remedy the problem. Fools rush in or something.

Removing the side plate, the mass of clockwork that makes revolvers work is revealed. Also a small piece resembling a 3-Iron falls out. Placing this carefully aside, observation suggests that the Do-Hicky that is supposed to hold the cylinder in place is pretty much free to float and rattle, which would explain the loose cylinder. The obvious solution is to install some shims under and over it to hold it in place. Over it is easy. Under requires that all the other parts be removed as this was evidently the first part to be installed at the factory. This principle was first developed by Sam Colt and Dan Wesson in the mid-1800s, and has been successfully applied to the automotive industry whereby the $.50 part that is expected to be the first to fail, requires the removal of the engine and transmission in order to get to it.

The revolver has six major sub-assemblies in it each consisting of a minimum of 3 parts, carefully cut so as to mesh like gears designed by a demented dwarf on acid, held in place by mutual pressure, one against the other, provided by springs capable of launching said parts into near earth orbit.

The first part to come out is the hammer, held in place by a 3-part spring assembly. The hammer is a 5-part assembly, not counting the main spring, which for some reason, stays together when removed.

The trigger is in 2 parts, the lower, which everybody is familiar with, and the upper, consisting of protuberances, recesses, slots, holes, pins and springs. The right side engages the do-hickey. The left side has a tongue that engages the Thingy, which is shaped like Pamela Anderson in a burlap bag. This is held against the trigger by a whacking big spring. The trigger is also home to the Blivett, shaped like California, floating on one of 3 pins embedded in it, and secured by swinging under an overhanging bit of the frame. Swing California back and lift it out. Did you hear the little click? Neither did I.

Pry the trigger and the Thingy up carefully. They have to come at least halfway up together on account of the Tongue inserted into the Thingy with Pam Anderson in it. Lift the Thingy out, holding your finger over the Whacking Big Spring to prevent launching it. You can now lift the trigger out, it’s Tongue lolling like an overheated dog, pushed down by a tiny spring.

The Do-Hicky is all that’s left, and rotating it down will clear the frame so you can lift it out. Again, with a finger over it as there is a spring behind it.

Insert a shim, about .005” thick over the Do-Hick pin, and begin re-assembly which of course is the reverse of the assembly. The 3-Iron and the Blivett fit into recesses in the cover plate, assuming you figured how to orient them correctly in the assembly process. When you are done, you will notice that everything works OK as long as the gun is pointed at your foot. If you try to operate it horizontally or upward, the cylinder will not turn, and the trigger will stick.

Dis-assembly is the reverse of the assembly. Remember that click you didn’t hear? Take the trigger and place the Blivett into its pivot hole, being careful this time to get the tiny Tongue Spring above the second pin. The Tongue does not require a spring, it just lives next to one. The third pin in the Blivett serves no purpose that I can identify. Don’t remove it, there’s a curse involved.

The gun now works normally, and has noticeably less wobble in the cylinder.

I have an exploded view picture of the gun. It’s about as useful as looking at a bomb crater and trying to reassemble the bomb. True, the picture has all the names of the parts, according to the factory, but a rose by any other name would still rattle.

Having done this, the gun has noticeably less wobble in the cylinder, and I only got one complaint about side spray at the last match, so I’m on the right track here. Professional advice, of course, is gratefully accepted.

Another obvious solution would be to get a new Do-Hicky, slightly thicker than the one I have, and with a tighter pin hole. If I knew a real gunsmith, I'd ask him where to get such a thing.

6 comments:

Pawpaw said...

While it's nice to dive in, unafraid, it's sometimes nice also to know what the parts are called and how they line up.

Hence, shop manuals. They're great. Might I recommend anything by Jerry Kuhnhausen? Wonderful books on how a particular gun works. His treatise on Smith and Wesson revolvers is required reading.

Billll said...

Since my Rossi is a good ringer for a Smith, the book would probably be quite helpful. Best price is $40, used.

I have a Gun Digest book on pistol smithing. Things to do are described, but a few more pictures wouldn't hurt.

The revolver mechanism is easy to understand as all the parts, except for the cylinder, move in only one plane. I'm thinking a new cylinder stop would go a long ways toward mitigating the problem.

Now to find one.

Anonymous said...

http://www.brownells.com/ Should have all the parts you need, and as you all ready have an exploded diagram you just might be able to use the part numbers on brownells site. Good Luck!

Robert said...

"Some people may not realize this, since everybody always talks about how 'simple' revolvers are, but the inside of a Smith & Wesson double-action revolver is the scene of a complex mechanical ballet that makes the guts of an autopistol look simple. A Glock or 1911 is a stone axe by comparison."

-Tamara Keel
"No User-Serviceable Parts Inside"
June 15, 2009

Billll said...

Automatic firearms take advantage of the fact that there's already a bimb going off in the users hand by arranging parts of the gun to deflect the shrapnel (cases) in a somewhat less threatening direction. Unless the shooter is wearing a tube top.

FWIW: Numrich had the part, a cylinder stop for you purists, at a reasonable price, and it's on its way.

I'll let you know if it helped.

Incidentally, the mechanism of the keys in a piano is sort of a kissing cousin to the mechanism in a revolver. Regulating the mechanisms of a grand piano is good practice.

Anonymous said...

In addition to Kuhnhausen, give the video from AGI a try: http://www.americangunsmith.com/view.php?id=4

I always find these cheaper at gun shows.