Hey fellas~ I have just moved back up here from Texas and I bought an AR15 while I was down there. It was used and I was really excited to fire it when I got here. I went out to fire it and it would not fire the Federal .223 rounds I put in it. It would just dimple the primer. I put a new spring in it and now it will fire a couple rounds and after about three rounds it will not extract the shells from the barrel. Have any of you had troubles like this before? My buddy in Texas thought maybe the fella before me had used steel Wolf ammo and the lacquer on the outside of the shells had transferred to my barrel and then when I heated the barrel up the brass shells would stick??? does that sound at all reasonable? Give me some ideas, thanks!