case bulging and splitting in factory cases. what could cause this?

[Trickymissfit]

Not wanting to contradict others on here, but the case bulge being on one side, or more pronounced on one side over the other, is common on factory rifles with a plunger type ejector. If the chamber is slightly oversize, the ejector pushes the case to one side causing the bulge to be more pronounced on one side.
This will most likely have little effect on hunting accuracy.

Normal partial full length sizing (PFL) may fix this, just bump the shoulders back .002" from where they are now. Chamber and see how it turns out.
If they don't chamber easily you may have to FL size them, but don't 'cam over', just screw the die in until it makes firm contact with the press ram at it's upper most point.
I come across this regularly in Remington rifles. The ejector springs are far too hard/stiff, I commonly swap them out for something a little less aggressive.

Is the WSM brass nickel plated?
If it is, I have never had good results with nickel brass and no longer use it in anything, and it's probably not the best brass for handloading anyway.

gun)

good post! I never gave the ejector pin much thought, but makes a lot of sense. I like to cut the spring back on mine to where the case literally falls right beside the rifle. I also polish mine a good bit with a little radius added to the head where it contacts the case. On the same thought, I've also ran into extractors the were causing the case to be missaligned (Remingtons). I fixed this with an M16 extractor.
gary