D man, after checking out the magazines, maybe the next thing to check is the extractor. Could be a simple matter of the extractor tension not being just right, or an adjustment of the extractor, or maybe you might try another extractor. The extractor is the heart of feeding and ejection.
It's not expensive to have them retensioned and adjusted, or install a new one from Ed Brown or Wilson, if you don't want to do this yourself it's still pretty cheap to have a smith do it for you.
Had the extractor retensioned and adjusted in my Springer Mil-spec, made a world of difference, and I just had an Ed Brown "hardcore" one put in just to make me feel better yet.
It's one thing at a time...after messing with mags, go with the extractor, you might not need go any farther than that for ejection...but if you do, next step might be the EJECTOR. If your ejector is just a tad too short, it won't kick out the spent round...also, if your using a buffer pad, it is possible your shorting yourself out on the length the slide moves back.
I'd say you cover all this, you should solve the problem of getting those empty cases out of that gun.
Good luck
Jimster