Getting ready for my next build, and need info on who's heavy or thick walled billet upper and lower receiver sets would be the best choice. And which would be stronger and better for the build. 6061 or 7075 aluminum. Gun will be used for target and hunting. Heavy match barrel 20" to 24" two stage trigger, forward grip free float tube, clamp on gas block and long distance rifle scope. any info or articles would be very appreciated. THANKS AND KEEP THEM IN THE RED !gun)