Shooting UK: check your barrels

hi stubbo here new member... just thought i would tell you about my dilema .i decided to take my gun to the local gun shop to trade it in for a new model because the gun is about 20 years old and to my horror the dealer found a pressure bulge in the bottom barrel about 6 inches from the muzzle .I was not aware of this bulge it was very slight even when you look down the barrels but if you look from muzzle end it can be seen.I asked what would cause that problem without me knowing.Possible cause could be a cartridge wad stuck in the barrel where upon another cartridge would be fired behind it and because the shot cant get away quick enough it bulges the barrels this is called a pressure ring.Another cause could soil or even a leaf of the floor easly picked up when your sat down in a pigion hide decoying .What i am trying to say is be vigilant and look down those barrels after each shot it is very easy in the heat of the moment to forget . one instance springs to mind is when there is a 2 man duck flush at a clay shoot its fast and fourius you do not have time to check your to busy looking for the next shot.This has been a bit of wake up call for me because i have been shooting for nearly 30 years hope this info is usefull to any newcomer to the sport this is firt time anything like this has happend to me whilst shooting it was good thing i went into that gun shop that day there could have been a serious disaster ..... be warned.....ps has anyone out there got a spare set of barrels for a 687 beretta