A device for restraining a shell in a barrel of a disposable anti-armour weapon being stored in a compartment of a transport box. A stopper member is configured to be placed in the barrel in front of and adjacent to a shell loaded therein. The stopper member has at least three radially expandable legs, which are distributed circumferentially and configured to face and engage a tapered front surface of the shell in the barrel. The legs are provided with gripping elements on radially outermost surfaces thereof and configured to cut into the barrel wall upon a forward movement of the shell in the barrel.