Early barrels had 1:14 twist 6 groove barrels which shot the 110 and 125 bullets just fine with the H4227 loads. New barrels have 1:10 twist 8 groove barrles which shoot the 110,125 &150 bullets just fine but develope pressure a little lower charge weights than the old barrels . Which one shoot the best ? The one you have ! Both 30 Herrett barrels shoot fine but have slightly different characteristics for what they seem to like for reloads. I sure would not stay up at night worrying about which one to get. Which ever you find in good condition and at a good price is the one you should get!