Years ago, I was asked to come up with the specifications for a tight necked, shorter throated 300 Weatherby. After It was built, I helped do the pressure testing, since there was no data available for that configuration. We loaded at the range, with a single case, that got pounded with pressure levels that were carefully worked up to but quite high. We had set up the neck diameter so that the correct neck tension worked out with a factory neck die. After the test, the case would chamber with no effort. This was somewhat surprising, given the pressure. We were quite a bit over the loading manual maximum. I attribute it to a couple of things. The chambering job was done with careful attention to headspace, so there was very little clearance between the front of the belt part of the chamber and the case, and although clearances from the shoulder forward were tight, I used the factory chamber body diameter specifications, having learned from a friend's problems when he had a chamber that was too close of a fit on new brass. In addition to having the tight neck, the throat length was set up so that 180 gr. hunting bullets could be seated slightly into the rifling, at a length that would fit into and feed from the magazine. This was in a custom stocked and barreled, German made Mk V. I did not recommend the configuration, but since the fellow that it was built for, is a very careful reloader, we did it, and I made sure that the testing was properly done. I think that the reason that some have had trouble with belted cases may be that there rifles were chambered with generous headspace (bolt face to front of belt) and because they followed die makers instructions to set the die to touch the shell holder, which would lead to separations.