DG,
The term "accurate" may be somewhat variable from user to user.
I said Brennekes and Fosters can be "reasonably" accurate to 100 yards in a smoothbore barrel, in matching a load to your own bore, and with sights.
What's "reasonably accurate" in that context, for me, is 6-8-inch groups. Some shooters and some guns can do better.
Others may feel that's not accurate, or sufficiently accurate, by their own definition. I'd say the term is a relative one in that 6-8 inches is poor accuracy in a rifle, but in a non-rifled shotgun designed for multiple pellets, that's actually not bad at all, and certainly viable for either hunting or self-defense uses at that distance.
A saboted bullet generally offers better accuracy in a rifled bore WITH good sights. The bullet is designed for better ballistics in terms of both aerodynamics and terminal performance (flies better in bucking air resistance & SHOULD retain better accuracy farther with its "bullet-shaped" profile than a slug of either type, and it's designed to expand during penetration) on most lighter animals.
The sabot engages the rifling down the barrel, and once it drops off a few feet from the muzzle, it continues on as a true bullet, with stabilizing spin as it goes.
Either type of slug will engage rifling, and both will spin as they fly. That adds a certain amount of stabilizing influence, but the blunt noses and cylindrical configurations will not provide the best aerodynamics as they go.
On deer, all three types will work just fine, assuming you place them correctly. Your odds of doing that at distance increase substantially with sabots in a rifled bore with sights. More so with a low magnification scope mounted. In such cases you're essentially converting a shotgun to a rifle, firing a bullet, and you can & should expect better long range performance on appropriate targets.
Slugs of either type CAN be very viable through a smoothbore at 100 yards, but for most of us to achieve it the gun has to have real sights. In a recent discussion of this issue elsewhere, a couple posters said they were able to use slugs effectively in their bead-sighted smoothbores out to 200 yards. I can't, and I'd say they're the exception.
I'd assume your 26-inch Remington Model 11 has a bead sight, in which case it's hardly surprising that you find your practical accuracy limited to about 50 yards. I've taken slugs a bit farther with a bead, but I consider 50-75 yards about average in realistic expectations.
Regulation with beads is often problematical, they may or may not put a slug anywhere near point of aim, which increases the difficulty of placing one where you want it as distances increase and you have to hold over or under. Beads also don't provide repeatable reference points in sighting like real sights do, and you can't match up point of aim with point of impact with a bead like you can with sights.
I'm not saying there's little reason to use a saboted round. They can extend the effective hunting range of a rifled barrel with sights over slugs in the same barrel. They do so at the cost of less penetration, which is more important in certain defensive applications (large hostile critters that may come after YOU) than in hunting smaller animals like deer.
In my own case, since I don't hunt with a shotgun, I prefer either the Remington BuckHammer or one of the Brennecke slugs for ATV carry in high timber as a defensive package. All three of my 870s have sights. After some years in policing with a bead, I will not handicap myself with one again.
That's just me.
Last week I was working with an inexpensive Savage/Stevens 350 shotgun with 18-inch smoothbore barrel that put three Brennecke slugs into 1 7/8 inches off the bench at 50 yards. WITH ghost-ring sights. No doubt that combo would easily hold hunting accuracy out to 100 yards & beyond if it had to. Conversely, another brand of slugs put three into 8 inches at the same distance in the same gun.
Matching your gun & load is important for best accuracy, and every shotgun barrel's different in what it likes best.
No need to be confused, it's just a matter of understanding the variables and not trying to equate the three projectile types equally in application.
Slugs can be "reasonably" accurate through a smoothbore to 100 yards, can be more accurate in a rifled barrel, assuming sights & not a bead for either use.
Saboted bullets can extend that useful range farther in a rifled bore, again with sights.
Some people may very well be phenominally accurate with a beaded smoothbore, but for most of us it's infinitely harder to do than with real sights, and most shooters can't maximize slug effectiveness with a bead.
What works "best" and what does or does not justify costs over other alternatives depends on the user, the platform, and the context.
I prefer the BH or the Brennecke because they offer decent accuracy at DEFENSIVE distances in my guns that are set up for them, along with hardened lead that's capable of deeper penetration and bone-busting than sabots. My applications don't include 150-yard deer hunting.
In a hunting context, using an appropriate platform (rifling & sights or glass), the sabots can offer superior range, accuracy, and utility.
You have to match the gun & load to the context.
Hog,
Slug diameters can vary, but most are close to the smoothbore's internal diameter. Standard slugs generally deal with different chokes by using the so-called "rifling" on the slugs to swage their walls down as they pass through the choke. They can be full bore size (or very near) and still not create excessive pressures at the choke.
The saboted bullet never touches the rifling anyway, the sabot does. The saboted bullet is much smaller in diameter than the inside of the bore.
Denis