Bear in mind I have not tried to reproduce this since (I went North and got shot no more than an hour later, apparently someone joined) but I did as follows,
1. Stand on the inside of the Tower facing the door and the ladder beside it.
2. Attempt to climb the ladder.
3. Your character should put down his/her gun and climb the ladder.
4. Dismount the ladder and you should be put back inside the tower and your AK should be also in your hands and on the floor.