I didnt post the incident because I thought it was funny, I posted it as a warning to others to how easily a tragic mistake can happen, I pulled a dozen shells out of a bag in the garage thinking they were all 10b, i sold the 3.5" 12 more than 5 years ago and didnt think there was any ammo left, as others have said I dont think there was too much danger until I had tried to fire another shell, long thin sticks are scarse on the marsh so I dropped a 5p coin down the barrel to check for a blockage and it didnt come out of the breech so I packed up and went home, the split case was jammed in the chamber so another shell wouldnt have loaded properly anyway.
Ive been out and sorted through my 10b loads this morning and found 2 more 12's which will go to my mate.
mike