Mine is also a 1-9 twist barrel. It shoots 35 gr. v-max ok, hates 40 gr. Nosler's and really likes the 50 and 55 gr. v-max. I have tried both IMR4227 and Lil'gun, I get better results with Lil'gun. It has taken 200+ rounds to get the groups to settle in, even after using flitz on the barrel it has been a work in progess. I am thinking about getting some of those bulk bullets Graybeard has been testing since it likes the heavier bullets. Good luck with yours, it sure is a fun round. JamesIII