A word of caution guys... The .410 is a calibre not a gauge and you could fire an old mild load 44 40 blackpowder cartridge out of them but a full choke .410 might blow up teh barrel with a .45 cartridge in it. Best get another gunsmiths opinion before you do mates... The .410 rifled slug is a 7/8 ths ounce .41 calibre ball that is traveling at the same muzzle velocity as a .44 magnum when it leaves the barrel of your shotgun. More than enough power there, why risk a blowout?

Yours, Aye. Dave