Swop barrel on a HW breakbarrel

[Murphy]

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

Also removing and reattaching the cocking arm.