please excuse myy spelling, bu I want to make brass barrells for a zsu-23-3 and other projects are ther accesble archives on thease wepons or are they classified, blue line drawings with diminsions is what i am looking for, are there books or online sources, or some one hat has one in the back yard. the company that mkes the barrell no longer makes it, but they still have an web account open and I will try monday to contact the, I come from a family of machinests so we could make them, or if some one has on to to coply demensions it was part # 3521