Tom was using a 30 caliber wildcat with 1-13" or 1-14" twist, loaded to 2600 fps (no mention of what bullet he was using). Tom said the 1-13" could only go 2600 fps without losing accuracy, but the 1-14" could go 2650+.
Tom buys into the "bands-stripping-in-the-rifling" theory of what limits cast bullet accuracy. I tend to disagree. I think my experiments with Loverider bullets have demonstrated that even itty bitty bands are able to hold the rifling without stripping.
However, it is a fact of physics that an unbalanced bullet -- and I assume all cast bullets are imperfectly balanced -- will wobble, and the faster they spin, the more they wobble. Hence my motivation to replace my factory 1-10 30-06 barrel with a 1-12. In hindsight, I might should have tried a 1-13 or 1-14, but maybe that will happen someday.

Benchrest shooters, both cast and jacketed, commonly shoot slower twists compared to the twist in hunting rifles. Obviously, jacketed bullets are not stripping in the rifling (though it is possible for the lead core to spin inside the jacket), so the fact that jacketed benchrest shooters also use slow twists backs up my suspicion that the issue is wobble, not stripping.
Anyway, I was particularly interested in the throat that Tom used. I may eventually copy it for my future rifle builds.
