Gun help

Well my gun normally worked, today i noticed my hopup chamber wont open on m16a2. Can anyone tell what could happen.

I plan on putting new hopup and inner barrel . So if im buying stuff i might as well oreder those parts also.

Well my gun normally worked, today i noticed my hopup chamber wont open on m16a2. Can anyone tell what could happen.

I plan on putting new hopup and inner barrel . So if im buying stuff i might as well oreder those parts also.