Swop barrel on a HW breakbarrel

[Bladerunner too]

This is interesting as the replies cover replacing the barrel / breech block as a unit. Whenever I see a 'barrel replacement' post I automatically think of just replacing the barrel proper i.e. the tube the pellet goes down, not including the breech block into which the barrel is fixed.
I must assume, therefore that if someone wished to swap calibre from, say, .177 to .22 on a break barrel the job would just entail swapping the barrel/breech block plus, most likely, an enlargement of the transfer port. Maybe an adjustment to the mainspring as well.
Cheers, Phil

As the .22 is supposed to be more air efficient ,i would think one would not have to enlarge the transfer port (in either .177 to .22 or visa versa) but certainly an adjustment of the mainspring.