Buddy of mine bough a saiga 223 version. Shooting brass PMC 55gr fmj's its beating up the casings badly. It dents in the neck, and give a nice scrape and dent in the case in the middle, and finally they show rubbing near the rim. This happens every time, on every shot. Whats causing this? My first guesses are extraction issue, or a gas issue of too much or too little? What your take?