Gate Peanut here, i've got a bergara barrel from m. b. tcs 1/14 twist shoots 1/2" and better at 100yds. 1" groups at 200yds. He puts his chamber(longer throat) in the barrels. I can seat the hornady #3505 180gr. SSp bullet and the 180gr #35771 out farther than normal max. barrels. Use AA-1680 thats the goto powder its not temperture sensitive, remington 7 1/2 SRBR primers, wow its a shooter. Peanut