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Old February 6, 2013, 12:26 AM   #1
4V50 Gary
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Join Date: November 2, 1998
Location: Colorado
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So today I disassembled a 5 screw S&W

The parts are a lot different from the 3 screw I was trained on!

On the three screw, the cylinder stop has a spring which is placed against the frame and provides tension for the cylinder stop to pop up. On the five screw, there's a plunger, spring and screw (in front of the trigger guard).

On the trigger of the three screw, a simple spring provides tension for the hand. On the five screw, there is a lever against which the hand is pushed up. On the opposite end of that lever is a spring. So, there's an extra pin that must be driven out to remove that lever. Talk about simplification of the design with the three screw.

The hand itself has a milled out portion that rides along the sideplate. It helps steady it and keeps it from wobbling. It is certainly requires a lot more machining than the one found on the three screw.

The sear on the five screw is a thing of beauty. It is like a tongue and groove arrangement with the groove being in the sear. The sear's tear drop shape gives a very gentle pressure curve when the hammer's tail engages it.

On the five screw, the hammer block does not ride on the rebound lever. Instead, it has its own plunger that is mounted in the sideplate. The hammer block remains in the sideplate and generally is not removed.

Seeing the insides of the older gun really makes me appreciate the engineering that went into making the three screw.

One of these days I have to look into a modern three screw with MIM parts. That's supposed to another animal.
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Old February 7, 2013, 09:06 PM   #2
James K
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Join Date: March 17, 1999
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Your five screw must be a very old one; the ones made from c. 1945 on had the hammer block actuated by the rebound slide just like the current ones.

S&W actually used three types of hammer blocks. The first was its own spring and fitted into the side plate. The hand actuated a plunger that moved the hammer block aside. The second type was similar, but the hand had a sloped surface that pushed a tab on the hammer block. That was the kind that failed during WWII, and resulted in the current "positive" block that is not dependent on a spring to reach the "safe" position.

If you want to really have fun, try to get hold of the original M&P, the Model 1899, and compare it with the modern MIM three screw. The many tiny parts and microscopic springs in the old gun will amaze you and cause you to wonder if they put those guns together under a magnifying glass.

S&W has been criticized for their "cheap" modern design. But if those guns were made like that five screw or like the 1899, the cost would be out of reach for most of us.

And possibly the most interesting thing is that through many changes and improvements of the internal design, they kept the external appearance the same (right up to the installation of the lock). Few people actually get to see the inside of the old guns as you did, and understand the differences.

Jim
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Last edited by James K; February 7, 2013 at 09:13 PM.
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Old February 8, 2013, 07:56 AM   #3
4V50 Gary
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Agree with you James that if S&W made five screws today, we coukdn'l afford them. The machining is fantastic and I don't think MIM would hold up to the stress that those milled parts could take.

BTW, the barrel is canted slightly at 11:30 and I'll have to drive out the pin to rotate it to 12 o'clock. If that doesn't work it will have to be turned down on a lathe.
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Old February 8, 2013, 04:22 PM   #4
James K
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There is something odd if the barrel is canted that much. The whole idea of the pin is to keep the barrel from turning since S&W did not tighten their barrels then to a crush fit (they do now, and have eliminated the pin).

Use a cup end punch to drive out that pin and you may find someone was there before you and the cut in the barrel is oversize.

Jim
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