Hi Philly: First I want to compliment you on your choice of slug gun, I set up a 220 for my brother-in-law this year. We put the 2x-7x Nikon Prostaff on it with Leupold rings and I was really impressed. The feel and balance is great, and it is a tack driver. We were virtually touching hole after hole at 100 yds with it. As far as scopes, I don't think there is a finer scope for the price than the Nikon Prostaff. But why do you want a BDC reticle when you are going to use a round that is pretty much flat out to 200 yds? Besides, if you don't use a round whose ballistics match those circles, all they are going to do is create more confusion. If you use Barnes Tipped Expanders, set the gun 2" high at 50 yds, you will be pretty much dead on at 150 yds, about 7" or 8" low at 200 yds. Forget the circle nonsense, learn where the gun shoots with a nice, plain duplex reticle. Out to 150 you are still shooting straight on the body, at 200 you are still shooting straight on the body, just high body. By 200 yds you've pretty much exhausted the feasible range of a fast 20 ga slug anyway. To me all that circle stuff is nonsense, and they just clutter up a nice sight picture. Furthermore, if you don't have a good solid rest, and I mean SOLID rest, the long distance stuff isn't gonna happen anyway. I've killed deer as far as 204 yds, and I use a 1974 Rem 870 with a 1969 Redfield 2x-7x 32mm on it. I 've also killed a bunch of them over 150 yds, this all came out of necessity 'cause the only place I have to hunt is looking over an 80 acre field. My point is, definitely go with the Prostaff, the 3-9 will give you a much bigger sight picture, if you think you are seeing enough out of the 2-7, then that will do you. Go to the store and look through both of them, see what you like.Also don't forget to consider ring height when you mount the new scope. Sorry for the lenghty reply, hopr this helps some!!