Hi, I remember seeing a build thread on a 51K made from a G3 kit.Could a 53K pistol be made from one of the HK33 cut barrel kits and 53 flats being sold now?There are a few issues I want to figure out before I get a kit,like will I need a different locking piece and can I buy a cocking tube or will I have to modify the one in the kit. - Thanks in advance