Sub Caliber barrel liner

Blastattack

Blastattack

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Hey all. Does anyone know of a company that makes custom O.D. rifle length barrel liners? I have a very nice Lee Enfield No.4 MKI, as well as a complete .22 LR bolt, and was considering making a .22LR sub-caliber device for the rifle. Something similar to the Erma K98 conversion kits or the .22LR FAL conversion kits, but have the liner secured at the muzzle with a nut. I know that a number of companies make liners, but most are a straight 5/16" in diameter. I would like to have the main portion of the barrel at finished diameter (.301"-.303") and have a section at one end that is both large and long enough to cut into either the shape of the chamber/chamber, or at least be big enough to put on a "normal" thread, and not a super shallow and super fine thread like the muzzle.

For reference, here is what the ERMA kit looks like my design would be sans the built in receiver and bolt, of course.

9387047_1.jpg
 
It might be a snug fit down the bore but why not just sleeve a chamber sized and shaped piece on the breach end of a conventional liner and thread the muzzle end. You might be wise to use a find double thread at the muzzle and make a matching tap for the nut portion due to the thin wall thickness of the liner. Solder a piece on the breach first then turn to shape and dimension between centers to ensure that it is concentric to the bore

cheers mooncoon
 
mooncoon said:
It might be a snug fit down the bore but why not just sleeve a chamber sized and shaped piece on the breach end of a conventional liner and thread the muzzle end. You might be wise to use a find double thread at the muzzle and make a matching tap for the nut portion due to the thin wall thickness of the liner. Solder a piece on the breach first then turn to shape and dimension between centers to ensure that it is concentric to the bore

cheers mooncoon
Click to expand...
conventional liners are to large for .303
 
gaff said:
conventional liners are to large for .303
Click to expand...

That is the big kicker. If i can get at least the liner diameter done by the factory, that will make life much easier. Accurately, consistently and concentrically removing .010" from a 26" long, thin walled shaft is not a trivial matter.
 
Blastattack said:
Well that is pretty damn neat. Never seen a follower rest done like that before.
Click to expand...

That type of rest is a bit more common in the world of turret lathes, lathes that were made to make a LOT of same type parts, in the pre-CNC days of production machining.

Another type of box tool to consider is to make a double bushing unit with a bushing on each side and the cutter in the middle. The bushings need to be a good fit on both sides, some set-up test cuts on similar materials would be needed, but once set up, would allow you to rip off the outside of the liner tube in a single pass.
Easier to make than the adjustable follower rest too.

Yeah, having a screw behind the cutting tool is a good plan, both for adjutability as well as to prevent it backing off.

This type tool is generally not used for onesy-twosy work unless the work really demands it, mostly due to the fiddly nature of setting up. Once set up though, they are the stuff!

In a production set-up, a station might have something like a hollow mill to start the end of the bar to size, or just a turning op, so that the rest of the bar would feed through the box tool.

Fun stuff! Unless you hve to put in an eight hour shift making the same bolt again and again.

Cheers
Trev
 
I think the intended use of the tiny follow rest is
-start the cut close to support (heavy end of stock or at the chuck)
-stop and apply the rest to your new diameter
-continue the cut supported...

It's cool! Definitely one way to turn down some .22 or .177 barrel liner. It's on my project list.
 
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