Sleeving a barrel

[kombi1976]

I've always wondered what exactly was involved in sleeving a barrel.
What's the process?
Is there a minimum change in bore size to do so i.e. 308 to 270 or 7mm to 6.5?

[John Traveler1]

Kombi,

Sleeving a barrel means to bore out a barrel with worn or damaged rifling/chamber to accept a new rifled insert.  The insert is usually soft soldered, but rimfire sleeves can be epoxied in place.  You get a new bore and chamber but retain the old barrel contour and markings.

Sleeving was commonly done to rimfire barrels or to obtain a shootable firearm when the ammunition is obsolete or prohibitively expensive.  The various obsolete .22, .25, .32, .44 rimfires of the 1800's leaves orphans that can not be fired unless the barrels are converted.  This is not commonly done because of cost factors.

Large caliber rifles can be sleeved to smaller calibers.  The limitation is a thick enough sleeve to machine easily, and provide sufficient chamber thickness for safety.  Old barrel thickness must be enough to support the sleeve.

High power centerfire barrels are rarely sleeved to original caliber for safety reasons.  Some Spanish arsenals sleeved 7x57 Mausers back to their orginal caliber, but that was an exception. Some Civil War blackpowder arms (Sharps, Springfield Armory, etc) were sleeved to accept smaller cartridges during the muzzleoading to cartridge transition era.  Generally, this was done when man/machine labor was relatively inexpensive decades ago.

If you are asking about reboring (re-machining new rifling into an old barrel), then yes, the new caliber is limited by the amount of material that has to be removed to get fresh rifling grooves.  You usually have to go at least one caliber larger to get this.

HTH
John

[gunnut69]

I've never seen anyone sleeve a high pressure rifle type round.  Usually 22 rimfires and pistol calibers are all that can be relined.  They can be relined to the same caliber so there is no need to change. Shotgun barrels are sometimes lined to increase the choke available..  I have seen adds for liners in lower pressure rifle calibers such as 38-55 but have no knowledge of how well they work.. High pressure rounds such as the 270 will rupture a liner and cause catastrophic barrel failure.. One can 'rebore' a barrel from one caliiber to a larger caliber. This is sometimes done to keep a weapon original on the outside while allowing it to be used..  There are some limits as to the size a given caliber can be bored to but I believe they are mostly based of the machine tolerances in the shop doing the rebore.