Recently took a defensive shotgun course, and the first day was spent patterning the individual guns with many different brands of 00 buck shot. It was all over the place. With that said my Remington 870 with 20" barrel, cylinder bore, rifle sights would put Hornady TAP 00 buck or Remington Managed Recoil 00 buck into a 16 to 18 inch circle at 40 yards. Bottom lilne is you simply cannot generalize about 00 buck shot. You have to pattern your gun with a number of different brands and find the one that performs best in your gun. I am not sure that I would want to go after deer with buck shot. I know studies have been done on that subject, and the number of wounded deer goes way up with buckshot versus slugs. With proper sights on your shotgun, you should have no trouble with slugs out to 100 yards or so. With the proper ammunition, you should have no problem with 00 buckshot out to 40 or 50 yards. The Hornady TAP uses some highly developed combination shot cup / wad that minimizes shot deformation, and keeps the shot together until it exits the barrel. It has "wings" that open up after it exits so the cup / wad sheds off. Very effective. Not sure what Remington does with its Managed Recoil stuff, but it is even more effective (in my gun) at longer ranges than the Hornady is. Buy a bunch of different brands, set up a patterning board at 40 yards, and pattern, pattern, pattern. You will come away with solid answers about what you and your gun can do at that range. Answers that no one can give on this forum.