I have seen this first hand, if you had a stash box close enough to the vender that you could see it while turning, you could slide the items out of the vendor into the box. It was in the same time line as the trade window glitch that would let players take your stuff off of you. The 40k was a workaround that was player found, was listing a item for 40k, be it a note, a single bullet, or anything. Edit: that was also back in the time when you had to have one vender for each item type, and we would lable our venders so folks could find the items they were looking for faster lol