My 870 loves light field 2 3/4. They group about 2.5 at 75. It's sighted 3" high at 75. I have a rifled cantilever barrel . My ithaca is smooth bore and remmy sluggers work best in it with open sights. Get a couple boxes of different kinds and see what "your" gun likes best. Everyone's gun is a bit different and likes different loads
Shotguns can be as picky as a .22lr about what it likes best. If your state allows rifled barrels get one then its still trial and error to what find what you can live with. I will say for a group of us for a shorter range slug , think heavy woods, remington buck hammer shoots well in all our guns smooth or rifled. For a more open shot I like hornady sst 300gr sabots. Good for a 3" 125 yard group zero. Diedly to 200yards maybe a bit farther for me. Scoped of course.
Remington 870 wingmaster smooth bore 28 inch barrel. Winchester 1oz rifled slugs have dropped deer at 200 yards (I admit lucky shot) routinely take deer at 100-130 yards.
Test your shotgun with different brands, usually rifled slugs wont fly very well out of rifled barrels (rifling on barrel wont match rifling on slug)
Sabots work best out of rifled barrels, sight in at distance you expect to be shooting at.
Buy 1 to 2 boxes of several different brands and try each one out. Go with the ones that give you the best groups at your sight in range. The prob;em with recommending a certain round is that what works in one gun perfectly, may worl like [email protected] in the same make, model, and gauge for someone else. A prime example:
i have 2 Mossberg 200Ks one love Winchester 2 3\4 inch 1 oz. slugs, the other one prefers Federal 2 3\4 inch slugs, but both run acceptably with Remington 1 oz slugs in 2\34 inch. Just depends on the gun.
As stated above, buy 'em and try 'em. Best of luck.
I used to hunt a little with my 870 with non choked smooth bore 20" barrel.I used 12 gauge 2 3/4" rifled slugs, specifically the Winchester Supreme Rackmaster rifled slugs (1 1/8 oz @ 1625 fps) and wow what great slugs, super accurate and one year I knocked a button buck off its feet from 25 yards with no pass through.