223AI to be exact.....Haven't measured the twist myself, but seeing as it won't do all that terribly well with the 53's, I'm guessing fairly slow.....
Suppose I should break down and actually measure it. Definately no quicker than 1 in 12 at any rate.
Don't get me wrong, it shot the 53's, but wouldn't go sub-moa with them....The 45's go way sub-moa....Same as the 40gr vmax.