i believe they make a huma reg now for those that should have enough "stored air pocket " we call "plenum" to get that , A Tim Hill valve with a light weight valve spring in the valve "Tim Hill " will install that before sending , and a large polymer transfer port "get 2 " incase you muck one up , he has a correct "drill bit and ball hone" for the barrel to open it up " you'll want a light hammer and probably his lightest hammer spring " its a 292 or a 262 cant remember but you will figure it out , if you do something that your gun will do what your trying to do , probably add another hammer spring next heaviest one up just incase you cant get the velocity , both springs are short enough to get free flight , any way its fun to do and rewarding ! and a little bit of $ to do , ive done 3 of these , mine has some JSAR parts and ..... go look there too , ! have fun