Berger has listed it as .296. Pretty good, but I tested the Hornady V-max 40 at an astounding .288. Given the velocity advantage of the 40, that might be the better way to go depending on your intended use.
Berger recommends a 9 twist with their 50, but I know a couple people using them successfully in 10 twist 20 BR's. In fact, I know of a shooter that got it to work in a 12 twist 20-250 AI, can't remember the velocity but he's at 5000' or so....
Dan C