The tool for ar10 uppers. - Midwest Industries Upper Receiver Rod

Don't waste your time with any other vice block or rod. I've used them all and this is hands down the best too for muzzle devices and barrel nuts. This is the best way to get proper torque values and prevent any distortion or damage to your upper. You could also use this as a self defense bludgeon. It's built like a tank. It will be the last upper receiver clamp you'll ever buy.