OK - I understand. The model 1887's are really fun guns in cowboy action shooting or for black powder clay shooting. I do not think they are particularly rapid shooters.

I had a semi-auto 12 bore when I was a kid. I turned from a damn good shot with my single shot Sears/Roebuck Cooey break barrel 20 bore - rarely ever missing, to a 3-shot loser. I always fired 3 and rarely, if ever hit anything with the second or third, but go through the ammo, it did. That was a Remington, Sportsman 48 or maybe 58 seems to me.
I sold it and bought an overunder Baikal with vent rib- what a nice gun and learned to shoot all over again, becoming a passable shooter. Knowing I had only 1 spare shot, seemed to be much more demanding that knowing I had 2 EXTRA shots.

Whatever the mechanics actually were, it worked.