3, 4, 5 screw? newbie question

[Dueeast]

What screws are they referring to? Also, what is a "pinned" barrel? is it pressed in then pinned as opposed to threaded? and lastly, recessed ? Thanks.

[tipoc]

In the pic below you can see 4 of the 5 screws. The 5th screw was in the front on the trigger guard. You can also see the pin which retains the barrel. The barrel was threaded into the frame and then pinned in place.



Below the 5th screw.



Below is an example of a recessed cylinder. These appeared (and still do on all 22 long rifle guns) originally only on the magnum guns, the .357 and the 44. he practice was discontinued in the 1980s IIRC.

tipoc

[scooter123]

At one time, the S&W revolvers featured a total of 5 screws in specific areas. One was in the front of the trigger guard and retained a coil spring for the cylinder stop. When that was dropped they became 4 screw revolvers. At this point this refers to a total of 4 screws to retain the sideplate. Then the top screw on the sideplate was dropped by replacing that screw with a tab that fits under a leged in the frame. At this point we have the 3 screew revolvers. Note, with many grips there is at least one of the sideplate screws hidden by the grip and some custom grips my hide 2. I'll also note that the strain screw on the bottom front of the grip frame has never been counted, why I do not know but that's the way it's always been done.

A pinned barrel has a groove machined into the threads that screw into the frame. After the barrel is installed in the frame this pin prevents the barrel from unscrewing from the frame. Back around 1982 S&W started using an interference fit thread to accomplish the same thing, so pinning the barrel in the frame was no longer required.

Another term you'll come across is Recessed. What this means that the chambers in the cylinder had counter bores to provide support to the rim of the Magnums. With todays brass, casehead ruptures are exceedingly rare so this has been dropped except for the rimfires. BTW, this change also took place in 1982.

[Nimrod44]

Actually the top sideplate screw was the 5th screw, the screw in front of the trigger guard was # 4.

[Hondo44]

Originally Posted by Nimrod44

Actually the top sideplate screw was the 5th screw, the screw in front of the trigger guard was # 4.

Except on the I and J frames. The trigger guard screw was the 5th screw because it was eliminated first on these frame sizes. The 4th screw at the top of the side plate was eliminated next.

And the earliest K frames were '4 screws' with no top side plate screw, then became '5 screws' when that screw was added.

CORRECTION: Jack, Thank you, I wrote that incorrectly! The original K frames, .32-20 and .38 had all 4 sideplate screws but no trigger guard screw and became 5 screws when that trigger guard screw was introduced on the 3rd Model M&P HEs (Models of 1905).

[Nimrod44]

Hondo you're right! I've been hanging around with the N frames too much lately.

[Hondo44]

Originally Posted by Nimrod44

Hondo you're right! I've been hanging around with the N frames too much lately.

You're welcome. I figured you knew that. There's always exceptions to S&Ws and I frequently forget them too sometimes.

[JP@AK]

Originally Posted by Hondo44

There's always exceptions to S&Ws and I frequently forget them too sometimes.

Yes. And here's another. Some early HEs had four in the sideplate and lacked the one in the trigger guard. Yet another 4 screw combination. My .32/20 HE Model of 1902 which letters to March 15, 1904 is like that.
Cheers.
Jack

[JP@AK]

Picture of the aforementioned .32/20 Hand Ejector.
JP

[Dueeast]

Thanks, You've all been very helpful !!!

[Hondo44]

Originally Posted by JP@AK

Yes. And here's another. Some early HEs had four in the sideplate and lacked the one in the trigger guard. Yet another 4 screw combination. My .32/20 HE Model of 1902 which letters to March 15, 1904 is like that.
Cheers.
Jack

Jack,
Thank you, I wrote that incorrectly! I've added a correction to my post above. The early K frames, .32-20 and .38 had all 4 sideplate screws but no trigger guard screw and became 5 screws when that screw was added to the 3rd Model M&P HEs (Models of 1905).

[GF1]

It may also be worth noting that with the 4-screws and forward the ejector rod was threaded with a left hand twist; the 5-screws have a right hand thread. This was done to mechanically oppose the torque from firing that previously tended to loosen the ejector rod.

[Hondo44]

Originally Posted by GF1

It may also be worth noting that with the 4-screws and forward the ejector rod was threaded with a left hand twist; the 5-screws have a right hand thread. This was done to mechanically oppose the torque from firing that previously tended to loosen the ejector rod.

Ejector thread direction is another good one to sort out and another interesting curiosity, also convoluted however.

What you say is a rough 'rule of thumb' for K and N frames and although the change to left hand thread preceded dropping the 4th screw (front of trigger guard) as much as two years depending on the model, there can be up to about 3 years when some K and N frames with 4 screws were still right hand thread. One sure way to tell is to look at the front end of the rod for the turned ring behind the knurling to be sure it's left hand thread before twisting counterclockwise to remove. Now it's curious because one would figure that the larger calibers being more prone to torque and having the rod unscrew would have been S&W's priority for the thread reversal. Surely using up parts inventory had a lot to do with this.

However, I and J frames with the straight knurled tip ejector rod were introduced after the war with left hand threads. The exception is those sporadic guns still using the immediate pre war size ejector knob which are limited to very early post war production that are typically still right hand thread.

[spinnerbaitor48]

great info guys...i really enjoy tapping all of your knowledge on these s&w's....learning more every day about my 32long reg police that my grandfather left me.....