I killed another player, and took his backpack(whatever the 80 slot one is called) to a safe space. After looting his bag I left the city. While running away I stopped to drink water and noticed several pistols, a shotgun, vitamins, and a couple cans of food missing from my inventory. I went back to the same place I dropped his bag at and found them placed back in the bag. I took them back and made sure before dropping the bag everything was in my inventory. I made it to the next town and noticed most were gone again.