Is the bottom metal and trigger guard a different material on the Remington Bdl vs the Sps? I am wondering because I am in the process of buying a gun to start a custom build and want the better bottom metal and trigger guard. I thought maybe the Bdl was actual steel and the sps was more like an aluminum. Any help would be appreciated. Also, what are the thoughs on a blind magizine (top load) vs a hinge plate for a 300 win mag custom build?