When I first got my Krieghoff Teck O/U in .375 H&H it would not extract the fired factory cases. Period.

When I attempted to open the action, it would open part way, with the extractor extensions, which are fitted to the outside of the barrel monoblock, actually bending slightly. The tiny spring loaded rimless extractors never slipped over the rims, I simply had to use a cleaning rod to knock the cases out. Much like trying to clear an M16 in Vietnam.

I brought the rifle back to the Krieghoff factory (fortunately I had a stopover in Germany on my way to Africa) and they fixed it. I never knew what they did, nor for that matter how they had originally sighted the thing in with scope and iron sights, which they obviously had done, but it worked. I had them fit a spare set of extractors to both barrel sets (.458 WM and .375 H&H), but have never had the need to use them.

My objection to rimless cartridges in double rifles, as I have said before, is not to the lack of rims per se, but to the fact that they are loaded to bolt rifle pressures without the immense primary extracting power of the bolt action extractor or the strength of the bolt action lockup. Cases with tapering walls are counterintuitively the biggest problem, since the DR action gives to some extent at the moment of ignition, when the pressure is at the highest and the case obturates fully. Then, as the pressure drops, the action snaps back and the tapered case is wedged into the chamber. Straight walled cases, such as the .458 WM and others of that ilk, are much easier to extract, since they are not subject to the wedging actioni.