Alex, I know Dumoulin will supply sets of chopper lump barrels and fit them. I ordered an AYA No.1 20 bore last year (still waiting

) and I was going to have Dumoulin supply and regulate a pair of rifle barrels for it in .44 Rem Mag , which they do quite often for others, but the price quoted was, I think, unrealistic. However I should suppose they may be willing to sell chopperlump barrel blanks. I can get a contact name and number for you if you want. I'm not sure by the way but it may be worth a try