most are using a 30" or slightly less, 10 twist barrel. 91-94 gr of h1000 powder with the 300 gr SMK bullet getting around 2750-2850. 3000 is doable with retumbo but Shawn (Mr Edge) Carlock told me 1000 worked the best with the smallest ES and i haven't really tried anything else. i got very good results with 92 gr and went hunting. i can shoot the 250's a little over 3200 before the bolt gets sticky, again with 1000. retumbo will give higher speeds.