Loading changes, ie: lighter, heavier balls or slugs along with different powders and wad columns and/or crimps will all change the way the barrels shoot as in regulation.

There is much to work with prior to any thoughts of having the barrels split and regulated to a single load. If the barrels are Euro - they might be brazed and not soldered, making re-regulation immpossible. I know the Belgium barrels used to all be brazed in yer gone buy, I do not know about their firearms or Italian and etc guns today as to how they are joined.

The Italian barrels on my Kodiak rifle are brazed - pretty sure of that.