Yes, divebuddy, that's what gamekeepers did years ago in an attempt to artificially reduce the number of predators on their eggs and chicks. It would mean that the numbers of magpies locally was reduced .Nature intended there to be a balance of food and consumers of it. Me, I wouldn't shoot one; I am not trying to create some outdoor aviary in a garden ! It seems pretty pointless, unless nearly every gardener does it (and/or there are enough gamekeepers at it).
Otherwise, what is your thesis to explain the increase in numbers in gardens as against years ago?