It worked well enough to complete my upper build - Trinity Force AR15 Upper Vise Block

This vice block worked well for holding the upper receiver firmly and in place. The only difficulty I had was torquing down the barrel nut due to the tight clearance at the barrel end of the upper receiver. My torque wrench did end up taking a few small pieces out of the vice block when I was torquing down the barrel, but the damage was minimal and didn't effect the effectiveness of the vise. I plan to use this vice block on future AR builds and am sure it will work just fine.