I have a 243 and 223 axis., both hb. Got the 243 first, rockited it, helped but still flexy, I can touch the barrel to stock by applying pressure to the stock when holding the barrel. With the 223 I removed a lot of the stock at the barrel channel, stuck it on my mill, took down the sides as well as under the barrel, can't make the stock/barrel contact without heavy pressure(more than anything encountered while shooting), think free float on steroids, no problem with it on bags or bipod, won't touch. I did put rockite in the wrist(and stuck in 1/4x 3 hex bolt in the rockite) of the 223 extending 2-3" towards the butt, it does noticeably stiffen that area and helps balance the hb. I don't see any down side to this, its free floated(sort of) from the factory anyway, and barrel blocked rifles just have the barrel hanging out there. I also glued the plastic trigger guard to the stock which adds a bit more stiffness. I'm a pretty experienced wood worker so I'll make stocks for both rifles with birch veneer plywood using pieces stacked and glue-lammed when I have the time but until then it I'm good since I'm not a match shooter.
Brian