For the delta ring, you can use those rubber strap wrenches for opening tough pickle jars lol
Worked great for me!
As SINN said, use a vert grip on the top part of the RIS while trying to move that nut.
The G&P special force has a special barrel nut which REQUIRES an armorers wrench to be removed, but you shouldn't have to play with the barrel nut to move the RIS.