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James K · May 1, 2010, 07:59 PM

Here is the scoop on liners.

When a barrel is drilled and reamed for a liner, the bore is not perfect, and even the best workman cannot install a liner that will be absolutely tight all the way. Also, there must be enough gap for the solder or glue that will be used to fix the liner in place. Typical liners are fairly thin and if used with a high pressure round will expand outward to fill any gaps between the liner and the inside of the barrel. The result is an uneven barrel that is not good for accuracy, plus possibly being unsafe. In brief, the liner must contain the pressure by itself, which means they are limited to low pressure cartridges.
(For a .22 LR (.223" groove diameter) liner, the barrel is drilled to .315", so the liner wall is at the groove bottom is .046" (a dime is about .052" thick).

There is another way, but much more expensive, and that is to take a barrel of the desired caliber and turn it down, leaving enough metal to be safe with the intended ammunition. The original barrel is then drilled and reamed out so it is nothing but a hollow shell, with just enough metal to retain its shape. The new barrel (not really a liner in the normal sense) is inserted into the shell. This is done in rare cases where there is a need to retain the original barrel shape and markings but to make a shootable rifle. Since the former condition usually applies to collector pieces, and collectors rarely want to shoot valuable rifles, that kind of "lining" is both uncommon and horribly expensive. It is a lot easier and cheaper to simply install the new barrel in the normal manner.

Jim.

May 1, 2010, 07:59 PM	#6
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	Here is the scoop on liners. When a barrel is drilled and reamed for a liner, the bore is not perfect, and even the best workman cannot install a liner that will be absolutely tight all the way. Also, there must be enough gap for the solder or glue that will be used to fix the liner in place. Typical liners are fairly thin and if used with a high pressure round will expand outward to fill any gaps between the liner and the inside of the barrel. The result is an uneven barrel that is not good for accuracy, plus possibly being unsafe. In brief, the liner must contain the pressure by itself, which means they are limited to low pressure cartridges. (For a .22 LR (.223" groove diameter) liner, the barrel is drilled to .315", so the liner wall is at the groove bottom is .046" (a dime is about .052" thick). There is another way, but much more expensive, and that is to take a barrel of the desired caliber and turn it down, leaving enough metal to be safe with the intended ammunition. The original barrel is then drilled and reamed out so it is nothing but a hollow shell, with just enough metal to retain its shape. The new barrel (not really a liner in the normal sense) is inserted into the shell. This is done in rare cases where there is a need to retain the original barrel shape and markings but to make a shootable rifle. Since the former condition usually applies to collector pieces, and collectors rarely want to shoot valuable rifles, that kind of "lining" is both uncommon and horribly expensive. It is a lot easier and cheaper to simply install the new barrel in the normal manner. Jim.