Columbus seems to have more bittering potential than northern brewer, but if you are just using it for bittering Northern Brewer will do a good job, just add a bit more. .15 oz sounds good to me.
Primary: Pineapple Pale Ale
Kegged: Conceited Brown Cur, Summer Citra Cerveza
Bottled: Concord-Cherry Wine, Dark Winter Spiced Ale, Whitetail Amber Ale, Summer Gold Pale Ale, Irish Sunset
I made a lot of beer and I can't drink it all by myself...okay I can but I like to share too.