Some years ago, I got a nice pre-war Winchester model 12, matted rib grade, on which some fool had shortened the barrel a few inches, whether to remove a damaged part, de-choke it, or whatever, I don't know. It was still well over 20", tho, so a Cutts was the obvious answer.
At that time, George Madis, the Winchester expert, was still living, so I called him, and asked him how the Cutts comps were added at the Winchester Custom Shop if so ordered on a matted rib barrel (if on a standard plain barrel, they forged special barrels for the Cutts-equipped guns)
Well, the way to 'do it right' is straightforward, albeit a bit tedious. Even tho the original question doubtless referred to a plain barrel rather than a ribbed one, the basic technique is the same.
After removing the barrel extension and filing the rib down for the area to be used, I set the barrel up in the lathe with a suitable delrin chucking collar to protect the finish. and dialed it in by the o.d.
The barrel was slightly out of round, so I turned it just enough to very nearly clean up, that is, I left a slight low about 1/8" wide. The diameter at which it cleans up is meaningless, you just need a clean accurately round surface. You must, tho, note that diameter, as you will need to know it a bit later.
Then, I ground/honed up a suitable threading tool with which to cut a 40tpi thread, taking great care to get a clean, accurately cut thread on the barrel. The pitch diameter of the thread was measured with a good thread pitch mike suitable for 40tpi, and the pitch diameter noted.
Then, I made up the 'gage' or 'dummy' to be used for the i.d. thread of the Cutts adaptor. I made this gage to exactly duplicate the thread on the barrel, except that I was trying for .0005 smaller pitch diameter.
I just bought a best quality internal threading tool rather than try to grind my own....that threading tool point for 40tpi is really small, and I decided I'd rather pay the price to get one which had its point generated on a suitable tool and cutter grinder, rather than try to hone up my own.
The next step, obviously, is to make up a copy of the Cutts adaptor, cutting the internal thread to suit the .0005 under gage......this takes a bit of care to have the thread clean and the part cooled down when you try the gage.
After getting the barrel threads dead clean but for the very slightest trace of light oil, and the barrel clamped up in wooden soft jaws in a vise, I improvised a handle for the Cutts adaptor, warmed it a bit....but not nearly enough to begin to turn colour.....and quickly wound it onto the barrel.
After the barrel and adaptor had cooled, they went back into the lathe, and, this time, were dialled in by the bore. I turned and threaded the o.d. of the Cutts adaptor to suit the Cutts. The adaptor was faced so that the Cutts sight was a bit 'short' of its centring, to allow for final fitting later.
All that remained, after polishing/bluing the adaptor, was to clock in the Cutts to get the sight bead centred, which is easily done with the gun itself set up on a surface-plate, with a receiver side gently clamped to an angle plate.
With the Cutts torqued down, and the receiver side at an accurate 90deg to the plate, it was easy to set up two angle plates, one on either side of the Cutts, and measure from each angle plate to the Cutts sight bead.
Obviously, if the sight bead was 'x' thou out of position, one simply figures the amount which must be faced off the end of the Cutts to bring the sight correctly into centre. (I 'cheated' a little, and was glad that I'd done so, as the Cutts seemed to go a teeny-tiny bit farther around for the same torque, the second time)
Now, granted, doing all that is a lot more work than simply silver-soldering the Cutts adaptor to the barrel.....but that thread (the .0005 under gage actually is meant to have the finished thread being 'line to line' or at most an extremely slight interference fit) is a lot less likely to 'shoot loose', and, with the threads for the Cutts run 'in situ' so to speak, the concentricity of the Cutts tubes with the barrel is preserved, as nearly as might be.
cheers
Carla
