Re: 270 wsm bergers
I found that the 10 twist factory barrel will do a great job with the 140 Bergers and Accubonds. The .270 AB has a slightly better BC than even the 130 6.5 bullet.
With Norma Cases sized with bushing dies .307 and a Wilson seater you will be very pleased. I found that MagPro was almost a hundred fps faster than any other powder. I tried R-22, VV N-560, 4000MR, Retumbo, W780, IMR 7828, Superperformance Ramshot Magnum. I like Fed 215M to light MagPro. Your barrel will vary, my factory 1885 Highwall had a 28 inch barrel. I got nearly 3400 fps with the 140s.