I'm telling you I don't know what kind of steel and at what pressure the gas block pins are put in at but over the weakend I took the pins out of my Norinco M4 carbine. WHAT A PIA . The pin was stuck so I centerpunched it so that the tappered pinpunch would not walk. A couple of good hits and I shatered the pin punch which left a piece of it in my finger, I gave up on that idea and decided to drill it out on mydrill press. The first one drilled fine the steel was hard at first but once the cobalt drill caught it walked right through it. The second pin was not so easy.I started it by center punching it again and using a small drill started drilling. The drill would not catch and I started to bore a hole a little at a time. I thought I was deep enough to start the bigger drill and when I did it started good so I added presure and it walked. I was starting to get mad at this point but I kept it in check. I turned the block and gun over and started on the other side same thing started than walked. Now by this time I was totaly PO ed so I took a bigger drill and drilled the F**k out of it. To say the least I got the Gas block off but I thought it was totaled,but not so it was made out of steel. I welded and built up the block where it was mangeled redrilled aand it was good to go and workes flawlessly. I can hardly waight till my free float hand gard and new gas block with the flipup sights come in so all that pain and agravation I went through is worth it. Any one else have a story like this one please feal free to share. You know what they say misery loves company. F.K.