I was playing normally, I found some players in the airfield and after killing, I went to loot.
After picking up the M16 that was on the FLOOR (it was in her hands and after killing him she went to the ground), notice how there is ANOTHER M16 on her back, I thought it was another one but when trying to pick it up I pulled the M16 that was in MY inventory, when taking the magazine from the M16 in my hand, I took the magazine from the M16 from his back (Evidently it is the same M16).
After relogging the M16 on his back it disappeared and an MP5 appeared in its place, solving the desync.