I asked Mike about this once in an email. If I remember correctly, he said that 77 Barlows are rounded (my word, not his) at the butt, unless they can't be. Saw cut can't be, really, or so he told me. So smooth bone are rounded, wood is rounded, micarta is rounded. But sawcut is not so rounded. My big question...what will the jigged bone be? This is the first ever jigged bone 77 barlow. So we'll have to see. I'm thinking it will be like the sawcut, not so rounded.
I should note: the first run of 77 Barlows were different. The African Blackwood cover 77 Barlows from the very first run had butts that were not so rounded. That's one reason I've held on to my blackwood. Personally, I think Barlows should have the not so rounded butts. That's why my favorites of the 77s are the saw cuts (and my first run African Backwood). I understand that many prefer the rounded butts, too, so I guess I'm glad there's something for everyone between all the cover options