Everyone, or at least most people, these days knows that forensic scientists can match bullets from the same gun that were fired at different people, different times or different places by matching the unique marks that are made by the rifling (sp?) of the barrel. Can the same be done for shotguns? Could a forensic scientist examine 2 different pellets and determine, with the same amount of accuracy as with a handgun, that they came from the same shotgun? With out rifling, are enough unique marks made on the pellets as they leave the barrel that would allow analysis?
Not the pellets. Shotguns are smoothbore guns and don’t leave any distinctive markings onteh pellets themlseves. However, for certain types that eject spent casings, like pump-action shotguns, if the investigators find expended shells at the scene, they could conceivably match up extractor markings to identify the specific gun used. For other types, it’s possible for firing pin marks to be matched, I suppose.
To elaborate on what QED posted, the pellets themselves do not actually touch the walls of the barrel. As they are propelled down the barrel, they are contained in a plastic wad or shotcup. This holds the pellets together en masse until ejected from the barrel.
It’s not as cut and dry as most people think, as the same gun can leave different “groove signatures” on bullets. There are many variables that come into play, such as copper build up, carbon build up, cleaning method, differences in bullet type, differences in bullet velocities, barrel temperature, etc. etc. etc. Suffice to say, there is no guarantee that multiple bullets fired from the same gun will all share groove signatures within a small variance envelope.