Those of you that own the AR-556 know that Ruger has made the delta ring much better than your usual Mil-Spec push spring type delta ring. It's a threaded version polymer delta ring. I think Ruger knocked this one out of the park! But, it can be a PITA to loosen & tighten. All you need to do is go down to your local auto parts store and buy a 12" length of 3/8" rubber fuel line. Wrap it around the polymer delta ring like a strap wrench, squeezing the hose very tight, then loosen or tighten the delta ring. Until Ruger, or, some other AR parts maker comes out with a replacement version of Rugers threaded delta ring, upgraded to aluminum or steel, the current polymer delta ring will continue to "egg" or get "oblong" when loosening/tightening it, because it's made from polymer. One more tip, apply a very small dab of anti-seize to the delta ring threads.