Well I got the sling question sorted out (after careful study of images on Google).
But I had another question, after adjusting the gas setting and putting the gas piston and piston return spring back in, I noticed that when bolt is locked back and the rifle is pointed up the piston extends through its hole about one cm ... is that normal? I don't remember if that's how it was before.
Sounds like your piston spring is weak, or somehow out of tolerance. The spring should keep the piston contacting the gas plug or in the "forward" position.





















































