Drill and tap an older K frame Model 14

[ggidzinski]

I have a 70's era Model 14-3 that I want to drill and tap for a scope rail. I have a couple of rail options which all have the 3 holes in the same place. They all claim that these 3 holes work for a modern pre-drilled revolver so I assume that they reflect the current factory hole pattern. I see however that the forward hole does not line up with the single hole in my older revolver and is off by around 3/4 of the hole diameter. This makes matching up the rail in all 3 hole locations a problem.

Did Smith really move the forward hole slightly when they went to 3 holes in the 90's?

How do you guys handle adding a rail to an older revolver?

Thanks,

George

 

[steamloco76]

Yes, the newer sight bases are slightly longer and have the screw just a bit forward.

Check out Jack Weigand mounts. Smith Wesson scope mounts KLN frame Weaver WEIG-A-TINNY® Weigand still makes a drill & tap mount for the older S&W revolvers and it is a very high quality piece.

 

[ggidzinski]

I have this rail and it has the same issue as the EGW and Weaver. The front hole is off by a fraction of a hole diameter.

 

[TAROMAN]

I have drilled and tapped several older revolvers, 28-2, 29-2 and 625-3.
No problem with hole placement, the new ones are IN ADDITION TO the factory front hole, which is over the forcing cone.
I use my drill press with an X-Y table for precise alignment of the holes.

 

[ggidzinski]

I have drilled and tapped several older revolvers, 28-2, 29-2 and 625-3.
No problem with hole placement, the new ones are IN ADDITION TO the factory front hole, which is over the forcing cone.
I use my drill press with an X-Y table for precise alignment of the holes.

So do you rely only on the back 2 new holes in this case?

 

[TAROMAN]

So do you rely only on the back 2 new holes in this case?

No, there are 3 new (larger) holes for the mount.
The original (tiny) one isn't used.
The new factory D&T guns have their holes in the same pattern. The front hole is the new larger size. So, the mounts fit either the new guns or (when drilled) the old ones.
Just imaged the 29-2 I drilled.
You can see the 3 new holes. The tiny factory one is forward, over the barrel extension and does not penetrate through the top strap.

 

[ggidzinski]

No, there are 3 new (larger) holes for the mount.
The original (tiny) one isn't used.
The new factory D&T guns have their holes in the same pattern. The front hole is the new larger size. So, the mounts fit either the new guns or (when drilled) the old ones.
Just imaged the 29-2 I drilled.
You can see the 3 new holes. The tiny factory one is forward, over the barrel extension and does not penetrate through the top strap.

So a modern gun has 3 large holes but when you drill and tap an older gun you end up with 4 holes (one small original and 3 new large)? In either case the back 3 are always the same?

 

[TAROMAN]

So a modern gun has 3 large holes but when you drill and tap an older gun you end up with 4 holes (one small original and 3 new large)? In either case the back 3 are always the same?

That is correct.

 

[ggidzinski]

That is correct.

I'll have to go back and take another look at the gun and rails.

Thanks,

George

 

[ggidzinski]

Here is what I found out.

In 1993 they not only started drilling and tapping 2 extra holes in the top strap of a K frame revolver but they also changed the type of rear sight used. The newer rear sight assembly has a different location for the forward seating screw that holds the factory rear sight assembly to the top strap. It's more towards the rear by about 1/32" on the newer guns. If you open the cylinder and look under the top strap, the seating screw for the factory rear sight is lined up with the barrel/cylinder interface on the newer guns and further forward on the older guns.

If you buy an aftermarket rail for a K frame revolver and if that rail has a rear recoil lug then you are limited on the forward placement of the rail to the factory position and on an older gun the forward hole will not quite make the gun thread location. It is so close however that drilling a new hole is not an option.

The solution that I am going for is an EGW rail with no holes drilled in it so that my gunsmith can line up for the existing forward hole and put the 2 new holes where a modern K frame is drilled.

 

[Art Doc]

The horror...

 

[long colt frazier]

The horror...

LIKE, LIKE!

 

[Lee Barner]

try to find an older weaver 307 mount for K/L frames. requires no drilling and tapping. they some times show up on flea bay. good strong mount. I have one my 686. it is a 307S for stainless guns. lee