When they are built the muzzel(sic) ends are brrought(sic) together to be parralel(sic) and in such a way that the boers(sic) are straight and not bowed in or out.
Now this definitely needs some explanation. The bores start wider apart at the breeches than they end up at the muzzles. There is "Absolutely" no way both bores can be straight with out bows & end up "Parallel".
To my knowledge I have (Fortunately) never owned a gun which you had anything to do with building. Over the years I have looked at quite a few double shotguns & done some measuring on a bunch of them. I have never checked one which had the bores parallel for any portion of their length. They all converged toward the muzzle for their entire length.
In the L C Smith Plans & Specifications book a drawing is shown giving the amount of convergence for their 12ga bbls & the distance from the muzzle at which the axis crosses. I have checked several of my Lefevers & they would appear to be built to near identical specs.