I loaded up some more short 10s with black powder the other day for a shooting expedition last Friday. Was using Duco cement to fasten the overshot card, something I've done many times in the past with good success. This time, however, I noticed that the cement was thinner than I recalled; it was an old bottle. As a consequence I added extra. When we finally found fresh bottles at a hardware store, I confirmed that the "fresh stuff" was much thicker--but there was no room to reinforce the shells I had already made.
So, out on the range, with paranoia I loaded two shells into the sawed-off Parker, but only fired the right barrel. As I lowered the gun, the pellets from the left barrel dribbled out of the muzzle. Whoops. If I'd fired the second barrel, it could have been unpleasant for both the gun and the operator.
If you load your own full-length brass BP shells, be careful and make sure the overshot cards are fastened securely! And don't use old Duco cement!
As a side note, here's a graphic I did some time ago illustrating the "guts" of a brass BP shotshell (based on RMC brass):
The perils of old Duco cement
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