Ed Matunas wrote many years ago the reason he used mostly a 270 Win or a 338WM was that bullets of those diameters were essentially custom designed for the velocity of those two cartridges. At the time, the only commercially significant cartridge that used a .277 cal bullet was the 270 Win, same for the 338WM. That's why your 270 works so well. Contrast that with .308 bullets that are supposed to work at any velocity from a 300 Savage to a 300 Weatherby. A similar problem occurs at .284 caliber.
Of course, he worked for Winchester and Lyman during his career, so may have been a bit predjudiced in favor of Winchester factory loadings.
Your 35Whelan kills quickly and ruins little meat for the same reason my 338WM does the same. Moderate velocity and relatively large bullets produce a little hole in/modest hole out, and a liquified chest cavity in between. You can "eat right up to the bullet hole."
