The pin hole

[steelslaver]

I really wonder just when and how the factory drilled the pin hole. Once the frame is drilled for the barrel drilling the pin hole from one side wouldn't work very well. For one thing the little .050 drill breaking through off center on the barrel hole would very likely break it and it sure wouldn't start right on the other side. Drilling from both sides with the right setup might work. But yo still have the break through problem. Clutched drills?? Drilling with a hardened piece threaded into the frame with a void to accept and guide the bit might work. But, it seams to me the best way would drill the pin hole then drill and tap the barrel hole.

Does anyone know just how they did it.

I don't think they did it with the barrel installed as the barrel has a generous flat bottom notch instead of a 1/2 round hole from a drill. Maybe take s notched barrel, install it, then drill and have drill pass through notch

 

[A10]

I would guess, and it's just a guess, that they drilled the hole right after forging and milling and before any hardening or heat treat. I would think the barrels are threaded then the flat milled, then the barrel installed.

This is no doubt why they stopped pinning barrels! There had to be at least four steps in manufacturing eliminated.

 

[stansdds]

Yep, lots of extra steps for something that was not necessary. Many think the pin is what holds the barrel in the frame, but the reality is that all S&W barrels are held by the torque applied to get the front sight to the 12 o'clock position.

 

[A10]

Yep, lots of extra steps for something that was not necessary. Many think the pin is what holds the barrel in the frame, but the reality is that all S&W barrels are held by the torque applied to get the front sight to the 12 o'clock position.

My 29-3 is as accurate and well built as any of my other 29s I've owned. I did like the way the recessed cylinder looked, but as with the pin it wasn't really necessary. I think a non pinned transitional model with the recessed cylinder would be the bees knees!

 

[Hair Trigger]

From a machining standpoint, the most accurate way would be to thread the barrel into the frame and "time" it (sights properly oriented), then drill the frame and barrel together as one step; the holes between the barrel and the frame will be perfectly aligned, no internal burr on the frame. I would guess the pins would be set prior to finishing.

 

[steelslaver]

I know the pin is completely unnecessary.

I also know they do not install the barrel then drill the hole for 2 reasons.
#1 the notch in the barrel for the pin is way bigger than the pin and is not just 1/2 round. It may be the best way, but it isn't how they do it.

I have lots of spare barrels, I have dismounted and mounted lots of them.

#2 If you installed the barrel and then drilled the pin hole, when you removed the barrel, the burr where the dill went from frame to barrel would mess gall the threads a bit. But, once you tap the pin out and break the initial torque the barrels thread out easy and the treads behind the pin slot are pristine. Besides that having match drilled lots of holes, even when 2 pieces are tightly joined there is a spot where the tip of the bit is cutting on both parts at the same time. This induces a bit of chattering and a .050 bit will snap in a heart beat. You only have a tiny bit of material once you subtract the drill flutes. The drills cross section only has about .00147 sq in of steel. .025x.025x3.14=.0019625 then subtract at least 1/4 for the flutes and that givs you .0014718

IF a pinned barrel does not torque up exactly the same way as a non pinned one, the pinned barrel will move.

I have installed a barrel that over clocked in a frame, turned it back to proper alignment, installed the pin and you can easily turn the barrel 5 degrees each way.

I have to believe it is after forging and before the drill the hole for barrel and thread it. But, I am not sure.

One thing I do know is I wish they would have used 1/16" pins, punches are easier to come by as is pin stock. I had to drill out a pin in a pre moder 28 once. I tried every thing and it would not budge. I uses a 2 flute 1/16 end mill and drilled it out. When done I used a 1/16 pin. Normal people won't notice that the pin is .0125 over sized.