1.Mosin on the back (both times the mosin was painted too)
2.Paint the m4 (both times i painted it green)

x)One time i painted the m4 green,then found a mosin, dropped the m4, picked up mosin and took the m4 in my hand.(could pick up the first time), some time later dropped the m4 on the ground and couldn't pick it up anymore.
x)Second time i had a mosin on my back, found an m4, picked it in my hand. painted it green (it dropped it on the ground, i could pick it up the first time), some zombies aggrod me, i picked out my axe, dropping the m4 on the ground and after i killed the zombies, i couldnt pick up the m4 anymore.

3.Actually i remembered now, that every time that happened i had logged out with a weapon on my back and a weapon in my hand and when i logged back in, there was nothing in my hands, but when i opened tab, the weapon what was in my hands before i logged out, was at the bottom of the list of items and i could run full speed without anything in my hands and i could pick the weapon in my hands, but after i dropped it, i couldnt pick it up again. I think that's what is causing it, because it happened with a mosin as well yesterday.