There is a formula in the old military improvised munitions handbook to reload a primer, by making new compound, using strike anywhere matches.
You take the primer apart, and with a punch push the firing pin dent back out, re load the cup and reassemble. It covers doing this on rifle and pistol primers, but i see no reason it wouldnt work on shotgun primers.
As far as putting a regular primer cup in, they arent shaped the same, has anyone measured them to verify they fit? Shotgun primers are notably more powerful, i doubt they are the same.
Anyway, the match thing does work, but uses a lot of matches.