Very noteworthy Red, can happen to anybody.
As to the butt stock slam, it is the 1st method any smith would do, but not on the concrete, unless you were under fire or something like that, I prefer a padded work bench, shooting bench will do with a phone book for a cushion, as I want the muzzle above my head and face and those around me, the object is to put pressure on the charging handle, bolt, pump forend etc... and slam the butt to get extra leverage and inertia, because until the bolt and cartridge are separated, bad things can happen, and no one has access to the rim of the cartridge, until the bolt is out of the way. Semi auto handguns, the idea is the same, but normally done horizontal to begin with, muzzle downrange, weak hand firmly on the slide about midships, and use your strong hand to jolt the frame, like you were going for the gold medal, against the gripframe, if on the handgun that does not work, and we know it is a live round, in most cases, remove the mainspring, to take any potential pressure that might work to the hammers advantage. Once the bolt is out of the way, you can try to hammer out the cartridge with a range rod, but usually does not work, because, your hammering against a bullet, = soft, and the powder charge = softer, pouring penetrant to disable the powder and primer is my next move and wait, now you can also pour water = does not compress, into the barrel, not too much, and then use a range rod with a patch around it to get a good seal, and see what happens. Sometimes extreme measures are needed, and you want the cartridge to be inert when tried, I have had to drill through a live primer ( prayed made inert by the penetrating oil ) and use a tap to thread the flash hole, and the use a bolt to screw through the hole to pull it out, kind of like, disabling an explosive, but without wires or batteries.