September 23, 2010
Back when I had my gunsmith shop, I was frequently approached by the ubiquitous .22 rifle owner complaining of a bad bore or chamber.
More often than not, the bore was pitted by rust due to the past use of corrosive ammunition, or it had some other sort of internal damage. The owner was almost always looking for a way to repair the damage without rebarreling the rifle. In many cases with older rifles, factory replacement barrels just weren't available. Unfortunately, there was no way then--nor is there a way now--of filling those pits.
In some situations, it's possible to repair a barrel so it once again has a good, clean bore with no imperfections. The most common technique for salvaging a damaged .22 rimfire barrel is to install a liner. A liner is simply a thin, rifled tube. Another way to think of it is as a very small-diameter barrel. By the way, all the .22 liners I have used have been button rifled. This just means that a carbide button with grooves machined in it to form the rifling is pulled or pushed through the tube, swaging the rifling into the barrel. It's a fast and inexpensive method of making liners.
When using a liner, make darn sure you position the breech end of the liner at the breech end of the barrel. And yes, there is a breech end of the liner.
Generally, you can determine which end is which by a ring or groove cut into the outside of the liner near one end. That's the breech end. This groove was cut into the liner to allow it to be held in the rifling machine when the button was pulled through it. The button was started at the end that was held with the groove. If you inadvertently reverse the liner, your bullet will be moving against the "grain" of the liner, and that will often lead to excessive fouling or leading after just a few rounds.
Drill Out The Old Barrel
Installation is pretty simple. First, the bore in the original barrel is drilled out with a special piloted drill. The pilot, an extension on the front of the drill equal to the diameter of the original bore, is necessary to keep the drill bit from wandering side to side or up and down as it cuts the length of the barrel. This drill--or in some cases, a series of drills--opens up the diameter of the bore enough to allow the liner to be placed inside the barrel.
Fasten The Liner
The liner can be held in the bore a number of different ways. Traditionally, gunsmiths have soldered the liner in place, and this is the method described in many of the older gunsmithing books. Unfortunately, using solder takes a good bit of time, and it normally requires two people to do the job. One person applies the heat with a torch while the other feeds in the liner, applies the solder, and adds flux from time to time. It's a hot, messy job, and you always run the risk of damaging the exterior finish of the barrel with heat from the torch or with the acid in the solder flux. Over the years, I've soldered in a number of liners, and I have to admit that it's not a job I look forward to.
Another more modern technique for securing the liner is gluing it in place. If you're like me, the idea of gluing a liner in a barrel is a bit unsettling. What's to keep the darn thing from coming out? After all, it is just glue.
Those concerns may have been well-founded 20 years ago, but with today's modern epoxy, that just isn't an issue. I remember the first time I used epoxy on a .22 liner. The installation was really simple. I cleaned the inside of the barrel, removing all traces of cutting oil after drilling out the bore. The exterior of the liner was wiped down with a solvent to ensure it was also clean and oil free.
The breech end of the liner was chambered using a standard .22 rimfire chamber reamer. A plug was then placed in the chamber to keep the epoxy from getting inside the liner. A slow-cure epoxy was mixed and applied to both the exterior of the liner and inside of the freshly reamed barrel. After this, the liner was slid into place from the muzzle end of the barrel. Once the chamber of the liner made its appearance at the breech, the excess epoxy was cleaned away, and the plug was removed.
A .22-caliber "Go" headspace gauge was placed in the chamber of the liner, and the bolt was closed or locked into place. A gentle tap or two on the muzzle end of the liner with a plastic-tipped hammer ensured that the liner was fully seated against the bolt. The headspace gauge was removed, and the liner and barrel were set aside to allow the epoxy to harden and cure. Once the materials were in place and all the parts were prepped, it took about 15 minutes or so to put everything together.
That was all there was to it. Unfortunately, the first time I used an epoxy, I made a mistake and found that I needed to remove the liner and do it all over again. That, my friends, was when I learned to appreciate the true strength of modern epoxies. It took an incredible amount of work, including the judicious use of a torch, to get that darn liner out of the barrel. It was a lot more difficult to remove than any soldered liner I had ever seen or installed. I became a believer in epoxy.
The Devil's In The Details
This is a relatively simple process, but as with everything, the devil is in the details. Not every .22 rifle can or should be lined. A classic example of this is the old Remington Model 12 pump. It's a great old rifle, but the barrel doesn't lend itself to lining. The problems are the shape of the breech end of the barrel and the manner in which the breechblock contacts the barrel.
The breech end of the Model 12 barrel is sharply tapered on two opposing sides. These side tapers result in very thin support at the rear of the chamber. A further complication relates to the breechblock. When the action is cycled, the breechblock tends to slam into the rear of the barrel. That's fine with the original barrel, but when you line it, you have problems.
The rear of the liner is tapered to match the rear of the barrel, which results in portions of it being very thin. As the action is cycled, the breechbolt slams into the liner and tends to peen it over. This, in turn, leads to extraction and even chambering problems. I've seen numbers of these old rifles that were lined, and the breech end of the liner was almost always beaten in and deformed. The best way I've seen to deal with the Model 12 is to use a new replacement barrel from Numrich Gun Parts. Those folks are the only ones I know that can still manufacture barrels for these rifles.
Lining a .22 barrel can be done with nothing more than hand tools. While I almost always drill out barrels on my lathe, you can do it with nothing more than an electric hand drill. It just takes a bit more time and care, but it can be done. Brownells offers all the supplies you need, plus an excellent how-to instruction manual is free for the asking. If you're interested in this process, give
'em a call and ask for a copy of the manual.
It's possible to line some centerfire barrels, and I've done a few over the years. All of these have been limited to fairly low-pressure cartridges such as .32-20, .44-40, and .30-30. I do not know of anyone who lines barrels for high-pressure cartridges such as .30-06 or .308.
As for accuracy, I generally find that the lined .22 rimfire barrel always produces better groups than the rifle did before lining. Now, I know that's a bit like comparing apples and oranges. After all, the original barrel had such a terrible bore that it needed to be replaced. Still, I've found that good liners will provide better accuracy than you can normally expect from a similar rifle with a good, original barrel.
Lining is a great way to salvage an otherwise ruined barrel. While you can't fill the pits in a rusted bore, you can sometimes replace the bore. Lining allows you to do that and still preserve the original barrel. And if it's done right, there will be little evidence of any work having been done.
Until next time, good luck and good gunsmithing!