Meanwhile i've found some tips to solve this problem

{DayZ 0.58}

Currently the only way to take a stock hand gaurd off of an AK is to have the weapon on your back/ nothing in your hands. Double click the hand gaurd and it should appear in your hands - discard the stock hand gaurd. You can now attach a different AK hand gaurd/ AK hand rail. To attach weapon accessories to your AK hand rail, the AK hand rail must be painted black. (Green/ stock colours will not work!)

I solved it myself by running into the wall, leaving while doing that the server and reconnect, then i was standing 5 meters next to the house
yepahhh, let's keep rocking those zombies