The Mateba Semi auto Carbine. The caliber is 44Mag and the barrel length is 18”. A rather ungainly adaptation of the Mateba semi-automatic revolver:
(revolver image credit to THR Senior Member GunTech)
I don't find the Mateba revolver particularly unattractive own it's own; it seems well finished and of good quality. It's when someone decided to slap an overly long barrel, slabs of wood for a forward grip, and a stock that looks like five minutes of thought went into it that it becomes ugly. With a little bit of shaping, and an eye towards wood that is more than utilitarian, they could have had something unique and attractive at the same time.