In smoothbores Ive always got the best with Win. Foster slugs. Years ago I pulled Rem. Fed and Win. Foster slugs apart to mic the slug and found the Win to be the largest dia. I did it again about 2yrs. ago for my 12 and they still were but I dont know about now (only one way to know, if ya just gotta know the dia.), otherwise just shoot them and see how they do in your gun which is really what you want to know.
BTW, Rem 'Sluggers'(?) have been the worse for me though worked well for others, go figure........