Im going to be deer hunting this year with my 870 20ga. and am torn between what to do. Theres allota bears around where i hunt so i wanted to beable to make quick snap shots if necassary, but also wanted a good scope for out to 100 yards if i see a nice deer. I was thinking about just going with the rifled barrel with no scope mount...then again like i said id love to have a scope...Is there a scope thats fitting for my conditions? or should i hunt open sights...Another question, hows the accuracy with open sights from a rifled barrel out to around 60 yards? Good enough to get the job done?

O yea....also, what effect will my 20ga slug have ona bear so happen a freak attack occured?

Sounds like a 1-4 power variable would fit your needs. With todays saboted slugs, a rifled barrel slug gun should give you rifle-like accuracy at 60 yd, assuming you do your part. And, if you hit a bear in the vitals with that slug, it'll put his lights out right now.
However if you gut-shoot him, it won't matter what you use to do it.

But, frankly, I think, if you are talking about black bears, your imagination is your worst problem. We hunt around them all the time. They want absolutely nothing to do with you.

The bushnell slug gun scope is a 1-4 variable with a circle x reticle, it would be great for what your doing and it costs around 70 bucks.

i was thinkin a red dot scope.

Would anyone hunt with open sights?

Hunting with open sights is always an option, especially in close cover. But, even then I'd carry binoc's or something to be able to check out suspicious shapes or movement in the brush. Either way, it's good to have an optical advantage.

Im with Wingbone, when hunting on the ground there are always suspicious shapes and movement that I put glass on for minutes at a time. If you go iron sights get binos for sure.

Absolutely. You just can't go wrong. With any of my semi autos or levers, I like to use iron sights. Whats sad today is the skill of hitting with iron sights is being lost.

I would go with iron sights. No need for a scope when shooting deer at less than 100 yds. And don't let bears scare you.