Sorry for the slow response Dogman, with summer vacations, we have members that have been there done that, with the Acc Sys in Colorado. I believe I remember reading it is an option, the beefed up new gas block, or boring your gas block to fit the bull barrel. I don't know if there is any accuracy improvement or not. Personally I would ask Acc if what the advantages would be, and the cost diff. Maby by then some of our members will be back on line with us, and contribute an opinion.