I think Gnarled Horn is also a critical hit Atma you can stack with RR.

When I fought Rani with a brew(lol) as a PUP I was told that I should use VV RR GH or RR GH and SS

but that was just for brewing a NM.

However, I get plenty confused when using Atmas because you also have to think about the Puppet too, and usually I use the Mage Puppet so my I can't use all the good atmas I want. VV RR MM

Soloing with WHM frame looks like RR C&D MM

Gah. D:

But I don't see nothing wrong with your gear, I am sure buffs from other parties could greatly increase Stringing Pummel damage.