I use an action wrench, barrel nut wrench & vice grips with a piece of this leather in the jaw. The kind of leather you'd find from an old shotgun strap or leather belt. It about 3/16" to 1/4" thick, 1" wide & 3 inches long. Stuff it in the vice grip jaw, clamp down on the barrel, push the vice grip in the opposite direction of the barrel nut wrench while tightening the barrel nut.

Do the opposite if you're removing it.

Remember, you may want to take it off again someday so it doesn't need to be tightened to a pucker factor of 10. A pucker factor of 7 to 8 should be adequate.

I very rarely hear of anyone using a barrel block / vice that's 100% happy with it.

Try the leather in the vice grip jaw thing. Works great.