That's odd, since my experience is just the opposite. I have always found straight walled cases the easiest to extract. My theory is that every action (particularly double rifle actions) has a certain amount of "give", and when the action springs back, the tapered case tends to wedge into the chamber, where the straight walled case does not. My Krieghoff .458 WM double rifle extracted and ejected cases with ease, but the cases had an alarming tendency to stick tight with the .375 H&H barrels. Krieghoff fixed the problem, but to this day I don't know how.

I own several Mannlicher Schoenauer rifles, and although the bolt operates incredibly smoothly, because of the position and design of the bolt handle it does not compare with my pre-64 Model 70 Winchesters in smoothness of operation from the shoulder.

My experience with the .300 H&H in the pre-64 Model 70 has been ideal. I once waded into a pack of wild dogs on private property in Kenya with that rifle and emptied it, accounting for four dogs with five shots in about eight seconds. I have to admit, however, that I once fired five aimed shots in eight seconds with an SMLE, all in the black (about 6.5" in diameter) of a 200 yard reduced target at 100 yards.