[Rock]

I have a Dpms rifle and I could not be more pleased I have never had any problems one of the better quality AR rifles made......The differences between aluminum and steel is that steel will last longer quality/performance will be the same the steel will be a little heaver. and you can put a bushmaster upper on the dpms lower the differance in lowers is some take small pins and some use large pins (trigger hammer ect ) other than that they are the same.