There is a reason these are typically steel - 2A Armament Builder Series Aluminum Castle Nut

I was going for a "light" weight for an LR-308 build. I debated and researched reviews and decided to take a chance.I ran this nut on with a brand new AVID wrench, and was very cautious and watching the teeth to ensure they were engaged. Just as my torque wrench clicked at 40ft-lb, two of the nut notches gave way. Maybe if it were of 7075 aluminum. Live and learn. Add a little touch up paint and replace it next time. At least I'm not out a receiver!