The magazine was found on the airport floor by the party worker, who picked it up and handed it to CRPF police personnel yesterday, police said, but declined to give further details.
The jawan had lost the rifle and magazine in a melee when a crowd of more than 3,000 party workers surged forward to welcome Stalin on his arrival from Chennai.
The jawan, part of a five member escort team, noticed the rifle and magazine missing only when he was about to board the vehicle of the DMK leader.
Meanwhile officials said an enquiry would be held to ascertain how the rifle and magazine was lost.
