The shooter claimed that his electronic target wires were snapped for the second time in six months and alleged it was a deliberate act to derail his preparations for the national trials.
"It's really quite frustrating to find the wires damaged this morning days before I'm set to leave for Delhi for the trials... It was perfect yesterday afternoon.
"The target is installed inside the hall which remains locked with security personnel but they are clueless. Certainly, it's done by insiders with an ill motive," Karmakar, who has lodged a complaint at the Ultadanga police station in this connection, told PTI.
At the last Nationals, Karmakar finished second after topping the qualification round with 619.1 points.