...tread lightly Steve...
Patterning : What Dave said , use different loads to see what YOUR gun likes at what distance. Mossy with that bbl...I'd try the Rem 9 pellet 00 first followed by Rem #1 buck.
Holo works
pretty well - turkey and deer for instance - more
stationary targets if you will.
Sights - For Serious applications more suited for slugs, as are Red Dots IMO/ IME. "Some folks" set these up for short range Urban Serious, must like what Israel had done.
Elastic butt cuffs move upon recoil. Leather or fixed will impede off side shooting. That said I have kept extra rds on a Shotgun with elastic, if I grab to go I yank off and put cuff on weak side wrist. I can still fire weak hand / shoulder this way. Leather...extra rds for hunting, or such, NOT really for Serious, IF I do have to shoot weak hand, I know I am gonna bust up my weak side cheek pretty good. BTDT used the T shirt to wipe the blood.
Steve, who has been know to stay low fire one handed around the cover, a bone stock SG to keep body behind cover. The "stage" was do what you have to, "X" amount of body passes the cover - you are down" .
Then again I did "expose" tip of bbl , so "target was moved to aquire bbl" ...I shot BG target from strong side with 1911 - BG more exposed to me that way.
Not a timed stage, "just don't get shot stage " , meaning if I could crawl and run I was to do so.
There is a place for running and gunning...there is a place to just run and survive.
Training for both is a good idea.
I can sit tight and wait for the calvary real good...another stage we 'practiced'.
Then again I prefer front bead with mid bead . I learned to POINT not aim a shotgun. I'm too old, fired too many rds,and set in my ways to change I guess.