DUAL AR 5.56 / .308 CAL UPPER RECEIVER ALUMINUM VISE BLOCK

I bought this to install a barrel on a pistol caliber upper that happened to be billet. I had bought the action block set(clamping style that clamps around your entire upper)from another Co. and when it arrived didn't fit so I emailed the manufacturer of the upper and was told the clamp style action blocks 99.9% of the time never fit the upper since they're bigger in some places for strength that's why they're more money than forged. And was told to never use those type of action blocks to tighten down a barrel to spec due to crushing, marring, twisting, etcetera. They said they use these to install their barrel so I searched and found this and in the AR-15 slots(haven't used the .308 set yet)works great to properly torque down barrel nuts, flash hiders/comps, with zero damage to my $140 billet pistol upper. I recommend this to anyone that needs something like this.