Pre-Model 27 – gas ring diameter. Knowledge request.

[AR_Black]

I have a .357 Magnum (Postwar, pre-model number) with S-Serial number.
Manufactured between 1949-1955.
This model later became the “Model 27”

This revolver originally had a 5-inch barrel. Unfortunately, the original barrel is unserviceable, someone shot some squib loads and there is a bulge in the barrel. The frame and cylinder are in decent shape. I’ve had this at least 10 years but have never shot it.

I found a very good 3.5-inch Model 27 barrel (shown in pictures below), but to my chagrin the cylinder won’t close. Why? The gas ring on the cylinder hits the barrel extension. Further observations note the original 5-inch barrel has a “flat” milled on the bottom of the barrel extension.

Apparently later models do not have the “flat” on the bottom of the barrel extension.
Later models MUST have a different gas ring with a smaller OD (and a different shape, see picture below).
Can anyone verify this?
If you have a picture of the gas ring a later Model-27, that would be great!

Any ideas to make this revolver a shooter?

Here are suggestions so far:

1. Mill the barrel extension of the 3.5-inch barrel to have the “flat”. This is not feasible, I don’t have access to a mill – and I don’t have the patience to use a file.
2. Find and fit a cylinder with the smaller OD gas ring.
3. Replace the gas ring on the original cylinder.

I’m leaning towards option 3. I understand the gas ring is pressed in place and I do have the ability to remove it. Then I could press in a gas ring with the smaller OD.

 

[AR_Black]

The Kuhnhausen Shop Manual (1990) shows the “Model 27” schematic on page 121.
Part # 5529 is the gas ring.

Numrich lists several gas rings, unfortunately they don’t have dimensions.
# 306810 for K.L,N Frames
# 306880 for K.L,N Frames
# 316910 shows 27 (all dash numbers). Could this be the one I need?

Link --- Numrich S&W GAS RINGS

 

[AR_Black]

And finally, the only other gas ring I can find searching the internet is at Jack First. Quite pricey. This page does list dimensions, but also shows it is for the K-Frame.

https://jackfirstinc.com/product/sm...-1-62-437-oal-437-small-od-383-id-1031-4555r/

 

[daddio202]

No expert gunsmith here but I think easiest way to solve your problem is with a file. I don't think it would take that long by hand to put a flat on the barrel, just make sure to keep the file square and true. After all the flat on barrel is how the original was set up.

 

[armorer951]

Your remedy is what is stated in post #4 above. Assemblers at the factory routinely cut these flats with hand files during final assembly after the barrel has been installed.

It's not visible in the photos, but if you look closely at the cut on the 6" barrel, (with a magnifier) you will probably find file marks, not machine marks. These cuts were made to accommodate the gas ring/yoke dimensions found in the cylinder assemblies. In this case, this cut is made necessary by the design of the slightly larger mouth of the gas ring, which had to accommodate the boss (larger diameter) on the forward end of the yoke barrel.

In short, there is no other gas ring available. Your cylinder has the correct ring and yoke.....the new barrel will need to be altered so that the cylinder and yoke will fit properly.



Carter

 

[Alk8944]

AR Black,

The only solution to your problem is to cut the flat on the bottom of the barrel shank like the original barrel. just as Carter, Armorer951, said! Even if a smaller gas ring existed it wouldn't work as it still needs to fit the recess for it in the cylinder! If you look there is also a flange on the yoke. The flat on the barrel needs to provide clearance for that too.

You don't have the patience to use a file??? It will take maybe three minutes and 4-5 strokes! Just grind the teeth off the side of the file to safe-edge it if you aren't confident you can do this without damaging the frame.

About the barrel bulge. As long as there is just one, and it isn't within one inch of the muzzle, that doesn't make the barrel un-serviceable, just unsightly. It is only cosmetic. Rarely does a barrel bulge affect the guns accuracy. The only reason to replace that barrel is if it bothers you that much.