I can't speak to the Tobh O rings as I have not tried them yet, but I can speak to the CCI Militia O rings, which I believe is based on the Patriot. These O rings actually fit and are the proper diameter, but they are too thick. You cannot get the cap to slide down all of the way, due to the lip on the inside of the Mutation X. Believe me, I have tried to come up with some way to sure up that side cap on the Mutation myself. The one bad thing I have come across with this Atty. No other complaints thus far, besides the fact that I have to pick up my mod from the sides of the mod itself, as if I try to pick it up by the atty, the top comes right off.