Still on the shotgun, but without the fancy language this time.
Lessons Learned Part 2:
2A. If circumstances require you to fire your shotgun one handed, you should do so from cover, using said cover to brace said shotgun.
2B. If, when doing so the slide opens upon firing, do not assume that it has opened far enough to pick up the next shell, even if it has ejected the fired one.
Mas had said that the slide opening was a possibility, for Remington 870s, and seemed surprised that it happened on a Mossberg. I guess that spray-can gun lube is better than I thought, or the action on my Mossy is smoother than usual. Or, I suppose it could have something to do with having replaced the stock fore-end with the Surefire replacement, with light.
Anyway, the slide opened, ejected the spent shell, I slammed it shut, not realizing that it had not picked up the next shell, and the bolt was closed on an empty chamber. Since the chamber was empty I had to depress the Action Lock to chamber a shell. On the range doing a drill, this merely slows me (and potentially everyone else) down a second or two, but when the excrement hits the rotary air circulation device...
BTW, if anyone has been following these drivelings for years, I can say that the Surefire fore-end gave me no problem this time around, so possibly the issues I had during the FAS Defensive Shotgun class back in 2015 were due to the Magpul sling adapter.
I was also able to acquire a supply of Federal Low Recoil Tactical slugs, and Low Recoil 8 Pellet 00 Buckshot with the Flite Control wad, which may have also led to a less-punishing experience.
The other issue I ran into with the 'scattergun was due to having the "Persuader" version of a Mossberg 500, with the 20" barrel and full length magazine. The barricade/cover positions for shotgun call for bracing the front of the mag' tube against the vertical or horizontal cover as a rest -- thus Part B of Lesson 2 above -- but that full length tube puts the muzzle right there, which is less than optimal. Fortunately I had added an after market clamp-on forward sling adapter which served OK as a brace.