I noticed something odd (to me anyway) the last couple weekends at the range. The shell casings coming from my AR10 are very hot, too hot to pick up right when they're ejected. This seems normal to me. But shooting the very same FGMM out of my R700, I can catch the casing in my bare hand as I pull the bolt back and it is hardly even warm. The only thing I can think of is the AR10's gas system, but I wouldn't think it would add that much heat ...or is there some other reason?