Ruger 10/22 custom barrel work: Cut, crown, thread and fill sight dovetail

finished ruger 10:22 crown and threads 1

First produced by Ruger in 1964, the Ruger 10/22 semiautomatic 22 rifle has proven to be extremely popular with shooters. To date, more than 5 million have been produced. The first rimfire rifle I personally bought, was a Ruger 10/22. My buddy brought over the barrel from his 39 year old blued 10/22 (we happen to know the age because it is stamped “Made in the 200th year of American liberty” (below), which would be 1976).

He wanted to install a tuner on the end of it and the model he was looking at required a 1/2″x28 thread. While we were working on it, he also wanted to cut and crown the barrel to 16.5″.

This barrel was 18.5″ and equipped with iron sights from the factory. We will be cutting 2″ off the barrel, including the front sight base. This means the rear sight and rear sight dovetail are no longer needed, these will be filled with metal to blend with the rest of the barrel.

For this project, I ordered the following from Brownells:

All lathe work is conducted on a Grizzly gunsmith’s lathe.

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To begin, the rear sight dovetail needs to be filled. Brownells makes a mild steel 3/8″ 60 degree dovetail slot blank for this application (above, top).

The filler is cut longer than the dovetail, at least a .020″ overhang on each side. At this point a hammer with a polished face can be used to form the blank into the dovetail. While this process works great, I prefer to silver solder in my blanks. I think it is faster, however, if the barrel will be blued, the bluing will not take to the solder. Since this barrel will be Cerakoted, it isn’t a concern.

The mating surfaces are cleaned with 220 grit abrasive cloth and coated in No. 4 Comet flux. I gently heat the area with a MAP torce and allow Hi-Force 44 solder to flow into the dovetail.

Once the barrel cools, the blank can be trimmed with files (above) and abrasive cloth. Since I’ll be threading it, I’ll trim it on the lathe. To see how the blank is shaped by hand, please see Filling a dovetail sight notch with a blank.

Now is a great time to cut the Ruger 10/22 barrel to length. I like to cut everything on the long side, in this case we settled on an overall length of 16.5″.

A hacksaw makes short work of cutting off the barrel. Note the front sight base on the Ruger 10/22 is machined into the barrel, this can’t be removed by pressure or heat. If you wanted to reuse it, it could be cut off, bored, then be soldered over a tenon on a barrel.

Because the barrel is tapered, it is mounted between centers on the lathe. If it was a straight profile, it could have simply been placed in a chuck through the headstock. While I could have shimmed this barrel to hold it in a chuck, or held it in a spider, I think mounting the barrel between centers is the prudent choice.

The blank is cut down on the lathe.

I use the lathe to cut the blank until it is a few thousandths proud of the barrel.

A lathe file ensures the surfaces are level. Remember, oil and files don’t mix. Make sure all oil is removed from the barrel before using a lathe file.

120 grit abrasive cloth and some Do-Drill cutting oil are used for the initial polishing. Note how well blended the dovetail blank is with the surrounding barrel (the blank is facing you in the photograph above).

I follow up with some 220 grit abrasive cloth and oil. Finally I make a pass with a fine Scotch Brite pad. Since this barrel will be Cerakoted, this is as much polishing as needs to be done.

Time to focus on threading the barrel. This barrel will be threaded 1/2″x28. I use a high-speed steel right hand insert profile tool from Browne lls to cut the tenon. By convention, thread tenons are cut .002″ under size prior to threading. Since 1/2″ is .500″ as a decimal, (.500″-.002″=.498″) .498″ is the target diameter of the tenon.

A high-speed steel insert threader is used to cut the threads. I run the lathe at 220 RPM and feed the threading tool at 29.5 degrees into the stock. I lubricated it with Do-Drill cutting oil.

I head back with the right hand insert profile tool and clean up the shoulder behind the threads.

The tuner adapter fits well.

The barrel needs a new crown since the current crown was cut with a hacksaw and had the lathe’s live center placed in it.

I don’t own any piloted form tools that fit 22 rimfires (everything I have is for centerfire cartridges). Because of this, I will be crowning the barrel using a Manson muzzle crown refacing kit. If I owned rimfire pilots, I would have simply crowned the barrel using a form tool when it was set up in the lathe.

The Manson muzzle crown refacing kit shown above, uses a spring loaded handle (top left) to drive carbide tipped cutters (top center and right). The cutters are held perpendicular to the bore with an expandable arbor (bottom).