My barrel slugs .432, I got pretty lousy groups with cast at full velocity untill I stopped sizing 'em to .430. My molds drop bullets from .431 to .432 and the gun shoots them great! I've been pan lubing mine, but recently was able to get a .431 sizing die for my Lyman 450 sizer, and bullets run through that are shooting great. Before complaining too loudly, contact customer service, and ask what they allow for barrel tolerance (don't tell 'em what you've got unless nessicary at this point), get some larger bullets and shoot them and see what results you get, you may find it will shoot just fine. this is one of the great advantages of cast, the bullets can be custom matched to the barrel.
The sights are weird, not what I would have expected either, but a maker is free to change their product as they wish, so probably not much can be done there. Doesn't the One Ragged Hole sight use the scope mount holes for mounting?