Thank you brother,
so filling that hole is a bad thing, noted! So where were you when I was in that Korean 'strip club'? I could have used your 'holes not to fill' advice and direction there too!
anyway I did find a replacement for the front sling mount with a rail on it. it has a channel for the gas to escape, since it covers the mentioned hole. it's 60 bucks. for that kind of money, do you think that it would secure enough hold a steal bipod?