Well I did everything clear cache, deinstall and reinstall GMod but I notice after I became Medic the Hand Glitch was gone, I can only say I was having this glitch only after becoming a Regimental Regular Trooper
I known is not game breaking thing but it destroy a little bit the immersive of the Combat Part, as you can my Hand or part of the Arm get stretch out if I'm in First Person view.