I know the thread is quite old but it seems to be the most recent on this topic of replacement barrels.
If the reason for replacement is simply they have more than a ½ choke then the fix is simple and cheap: just ream out the choke. This should be quick and cheap with any gunsmith: if you are an engineer one can do it oneself using an adjustable reamer (hand driven of course to avoid chatter), followed up by polish using bronze wire wool. Dimensions are simple to look up. A ¼ choke has the same effect with steel shot as a ⅞ choke with lead so you are probably wanting to remove most of the choke constriction.
If on the other hand you need to replace the barrels because they are thin barrels, as are some of mine, then it is either a sleeve or an expensive replacement. I am working on a sleeve for some nice old Whitworth fluid pressed steel barrels that were thin even when new. Now, 130 years later, they are 20.6 thou thick 9" from the breech (and given the Whitworth steel they are probably OK down to 18 thou) but at 14" from the breech they are a mere 12 thou! That is just 0.3mm! Just remeasured them last night to start work on the tool to drill the barrels: with barrels that thin I do not fancy the risk of using a normal gun drill on them so doing a fixture than can be driven by a CNC spindle motor. Will take a few months before they are ready to go off for reproofing as spare time is limited just now, but when done will post again on here. Yes I am stuck with 2 ½" cartridges but for the things I use it for that is fine.
If the reason for replacement is simply they have more than a ½ choke then the fix is simple and cheap: just ream out the choke. This should be quick and cheap with any gunsmith: if you are an engineer one can do it oneself using an adjustable reamer (hand driven of course to avoid chatter), followed up by polish using bronze wire wool. Dimensions are simple to look up. A ¼ choke has the same effect with steel shot as a ⅞ choke with lead so you are probably wanting to remove most of the choke constriction.
If on the other hand you need to replace the barrels because they are thin barrels, as are some of mine, then it is either a sleeve or an expensive replacement. I am working on a sleeve for some nice old Whitworth fluid pressed steel barrels that were thin even when new. Now, 130 years later, they are 20.6 thou thick 9" from the breech (and given the Whitworth steel they are probably OK down to 18 thou) but at 14" from the breech they are a mere 12 thou! That is just 0.3mm! Just remeasured them last night to start work on the tool to drill the barrels: with barrels that thin I do not fancy the risk of using a normal gun drill on them so doing a fixture than can be driven by a CNC spindle motor. Will take a few months before they are ready to go off for reproofing as spare time is limited just now, but when done will post again on here. Yes I am stuck with 2 ½" cartridges but for the things I use it for that is fine.




