I have been offered a lovely little room rifle that has been bored out to a 410 shotgun. It’s octagonal barrelled with plenty of wall thickness.

How much of a job is to bore out the barrel a bit more, turning a 22 bore barrel and then setting this in as a liner and chambering it 22 hornet or a 5.5x50r - latter is legal for Roe deer. How much wall thickness do I need and are the actions strong enough?