The longer the bullets, the faster the twist. 50 BMG twist is usually 15 inches. My 450 Dakota twist is 14 inches, but I wanted a 10 or a 12. I could have obtained this if I bought a Krieger, but at the time I did not like the one year waiting period.

So, if I were building a 510 I likely would use a 15, maybe a 14 if I were using the short 535 grain Woodleighs. If I were using longer monometals, I would want a 12 inch twist.

The general thinking amongst accuracy fans is the big bores of the past had too slow a twist. Many were 18, even 20 inch.

And if you believe the A-Square hype, a faster twist and faster bullet rotation (higher RPM) increases the hydrostatic shock effect and the higher gryoscopic stability results in deeper penetration.