Hello Casper50,

Thank you for your comment.

I'm not entirely sure of this, but "every" Nitro Express Daniel Fraser Double rifle that I've seen pictured on the internet has the rib set-back from the muzzle like mine.

see this link .... 4th picture.

The caption reads, "Crowns on a Dan'l Fraser double rifle with rebated rib---theoretically to avoid bullet deflection from asymmetrical gas dispersion as the bullet leaves the muzzle."

http://www.hallowellco.com/crown.htm

If I'm wrong, please enlighten me.