I'll play ....
Using PMC's Brenneke slug (12 ga, 1 oz at 1600 fps) through a Rem 870 iron-sighted imp cyl 20" bbl. Set at 4" high at 25 yards (may change that down to 2") prints same-same at 50 - seems all but dead-on at 100 yards (no 75 yard tests).
Clover-leaf 3-shot groups at 25 & about 1" separation at 50. 6-7" groups at 100 yards, but that is
my fading eyesight - suspect easily 1/2 that with a scope or younger eyes. Right on the money for elevation though = no +/- ... looks to have a mid range trajectory of 4-5" ("totally flat" through 50 yards) & back on at 100 yards. Actually pretty amazing, all told, for (an assumed
) BC of about .005
Tried the same load through an Express Turkey (21" bbl, double beads, mod choke) & was about twice the groupngs. Don't know if the choke messed with the groups or if the sight system just didn't allow the same precision as did the iron sights. Hardly matters as this latter shooter's fairly standard with the mod choke & just wanted to see what it would do "as is." "Good enough to 50" is what I've decided, & plenty good enough to "keep their heads down" at a bit better than that (though wouldn't risk it for shooting game).
Waiting for a case of the PMC Brenneke 20 ga slugs to do some patterning with that ... seems long on arrival through local sources ... Expect similar results as with the 12s.
Only others I've patterned extensively is for turkeys & all through that 21" 12 & with Rem's extra full turkey choke, except for a few off-the-shelf Winchester 20 ga stuff (max dram, 1-1/4 oz loads in 4s & 2s/screw-in full chokes ... looking for a suitable-enough turkey load ... "good enough" through 30 yards & probablly an absolute hammer on pheasants, etc.)
Rem's Duplex were disappointing. For one, I could never discover what mix of the shot (= how many #2s versus the #4s , etc.) - besides them not patterning worth a darn.
Fed's Premium line of 2 oz of #4 patterned (at a measured 40 yards & on a life-size turkey body) wonderfully - averaged at a 27 conservative lethal head/neck hits per shot. Winchester's 1-7/8 oz #4s (25-count box loads) came in just under .... nothing to sneeze at for turkeys & come to think of it, one hell of a "close-in" defensive loading - ~200-270 #4 pellets in a 40 yard 30" circle .....
(Rem's extra ful turkey choke, if not mentioned)
Still have a coupla boxes of Active Penetrator 2-1/4 ox #4s that I've yet to touch off ... can't imagine they'd be a "bad load."
Fed's Premium 12 ga 3" mag #4 buck (41 .22 cal pellets at about 1200-1500 fps) in a modified 21" gives a nice coverage pattern about 2+ foot at 25 yards. Let that one sink in a bit ... (an estimated 20+ ~10/22-hit per inch over a 30" circle every time you pull the trigger .... ) ..... a tad expensive though & recoil's on the "up-side." But, how many ya gonna use?
Winchester's got some 25-per box 27-count #4 buck that seems to work quite well (thank you very much) to 25 yards at around $12/box in an improved. Patterns good enough, but doesn't have the pellet count as with Fed's 3" mag, but too, not nearly the recoil - allows vey quick follow-ups .... a "stand-by" loading for 2-3/4" receivers.
Random brain fart/dump from my own - your mileage will vary, but illustrative enough.