Its called black Friday because historically many stores would operate "in the red" or not having yet made a profit for the year prior to the weekend after thanksgiving. Thus after the busiest shopping day of the year they would be "in the black" hence black Friday. At least that's the tall Ive always been told.
And yes I believe most large retailers are going to have sales. Weather those sales will extend to .30-06 ammo I don't know, many have flyers they release ahead of time. Check Bass Pro, and Gander Mt would be good places to look.