You might also consider the Burris Fullfield II 3-9 w/BallisticPlex reticle for a couple of hundred. Works fine on my 580 Ranch, though usually I don't mount the scope; just use the scope to test ammo every now and then.
The BallisticPlex is a pretty cool feature on this scope. With a 100 yard zero the longer range dots line up pretty well on most ammunition.
Of course an untamed Ranch will eventually beat the living hell out of most reticle scopes so the idea of a red dot or whatever probably makes more sense, but then you really don't have a scope, do you?
Anyway, to me the 580 Ranch should be left the way it comes out of the box as far as sights are concerned unless you need to evaluate ammo; the rifle's sighting equipment is consistent with its intended purpose, for the most part, which is quick, off-hand shooting.
I mean you really don't think that you can hit Mr. Gopher in the melon at 300 yards with this rifle anyway, do you?
Because the stock Ranch, out of the box, just will not do it, scope or no scope. Of course the scope will help you to understand the "grouping" characteristics of the Ranch. Hopefully you will not toss the entire investment into a ditch after your intial outing.
I suppose there may be one or two folks who might be inclined to flame me for the next comment but make it I will: In my opinion a stock Ranch rifle with a scope is a fundamentally ridiculous arrangement in almost all cases (unless you are testing ammo) and serves to defeat the purpose of the arm. I like to keep track of what I am shooting at, you know, while I am shooting at it. Tube scopes don't help that very much.
Don't know about red dots and the like as I have never used one.
By the way, I really, really like my Ranch and would never part with it irrespective of it's performance limits. It is quick and handy, points well, and so long as you leave the large cap magazines at the gun show, it carries well in the field. It takes a lickin' and keeps on tickin', you know?
Simplicity, man.
But if you absolutely must mount a scope consider the Burris as it is a good enough scope for this rifle. It has always worked fine for me when I needed it and it is, so far as I can tell, good quality for the price.
doc