Yogi:
I'm always happy to be proven wrong, because it often means something very interesting has happened, but I think you'll find that the Dixie Slugs will tumble unless fired from a rifled (or rifled-choke) barrel. They have no way of achieving stability in flight unless spin-stabilised. The Brennekes use a plastic or felt base-wad which stays attached to the projectile all the way to the target, to act as a 'shuttle-cock' and maintain nose-forward stability. Even the humble Foster slug is nose-heavy with a hollow lead 'skirt' to achieve the same effect, though not as reliably as the Brenneke-type slug.

Give the Dixie slugs a go by all means, but I wouldn't be expecting spectacular results. In fact I wouldn't be expecting 2-inch groups at 50 yds from any smooth-bore slug-gun, though I'd sure be happy to achieve it!

I appreciate your desire to 'buy American' but the Brenneke is the industry standard, and would be my recommendation for the bulk of your efforts.

Keep us posted.