Well..... I think I actually did it once upon a time. I was reloading 20 gauge target loads (STS hulls, W-209, AA wad, 15.6gr. Universal Clays, 7/8oz.#8's) for use in an L.C.Smith Field Grade. Loading was done in a Mec 600, no auto primer feed. Several times I caught myself reaching for a primer instead of a wad. It was a marathon loading session, late at night, and I was tired. Not thinking that I had actually gone so far as to drop a primer in the wad guide, I continued on. The next day on the trap line one of the shells produced a report much, much louder than normal. Looking at the gun I noticed a chunk of wood missing from the upper RH stock cheek. I opened the gun (with much difficulty) and found the primer to have been blown- the gas from which no doubt blew out the wood. Everything else seemed normal. Even found the missing chunk of wood in the grass. Upon further investigation I noticed a fresh shell would fall into the the chamber further than it would in the other chamber. That's when I noticed a slight but definite bulge on the RH side of the barrel, right over the end of the chamber.
The previous shot had smashed the clay bird, so I'm reasonably sure there was no wad stuck in the forcing cone. Examination of the previously fired hulls turned up no missing pieces that could have lodged there also. Shaken (but not stirred), I went home. It was later that I remembered the incident of almost dropping a primer into the wad guide and have since come to the belief that I must have done so. Needless to say I dissected the remaining shells from that session- about 600 -only to find nothing but powder, wads and shot. My one brush with disaster gun-wise, and it was enough.
