Well you don't even have to worry about the scope/barrel part of your "equation" cause you got the scope and barrel, right. So that's 2/3rds of the equaltion. right? (and the 1187 is a darn good gun, your father must like you a bit)

WRONGO!

Now the biggest part of the equation. The question of all questions! The question that there is not, ever, one single correct answer.

Every gun is different and likes different ammo. Sometimes same gun combos shoot just like another exact same gun combo with same ammo, sometimes you might get drastically different results.

My gun loves it, I think it's great ammo. Your gun can't pattern with it and you think it's garbage. Etc. Etc.

First you have to dial that sucker into some sort of grouping. You might want to have it bore sighted at a shop or just head to the targets. Either way, I would use cheaper ammo for initial patterning. You may be perfectly happy with the results you achieve and stay there. But if you want to know what loads get the absolute maximum from your set up, it's alot of trial and error ($$$). You would need to go out and get your assortment of slugs and sit and shoot and shoot and shoot. (Maybe ice the shoulder). With the absolute great assortment of slug offerings out there today you can easily spend a thousand dollars trying slugs and still not try them all (figuring 4 boxes/20 shots of each).

But I will tell you this. In my years, I think Remington guns/barrels work pretty darn good with Remingtom slugs. Therefore, I am recommending that you give the Remington BuckHammers a call. For the distances you cited, 2-3/4" loads. If they don't give you good results I would be suprised. Thay are a little new on the market, but the one thing I keep hearing and seeing about them is they are consistent and fly true (no tumblers or keyholing).

On the scope, is there a small diamond around the cross hairs? (Simmons Pro-Diamond recticle?). And where are you in IL?