Okay, the problem we're looking at is extracting unfired rounds with a mag installed resulting in this:
The first guess as to why this happens is magazine springs being too strong. So I used my mark pistol whose bolt has the same feature that gives the extracting round clearance. I couldn't get the bullet in the mag to touch the extracting round until ALL the driving bands plus 1/16" were out of the chamber. This, even while prying the nose of the bullet in the mag upward with a dental pick! The reason the round in the mag can't touch the extracting round can be seen looking at the LCP2 breech block:
The extracting rim sits within the red circle. The yellow line shows all the material that holds the next round down in the mag. The mag is not the problem.
The next guess is Doc's "because there is no 'recessed area' on the breech" guess. This is wrong as well. The sides of the pocket are on the breech block, while the top is on the barrel face. A bit different approach, but WAAAY better than the Mark3 bolt! The LCI cutout on the MK3 bolt leaves only a teeny tiny point of material to hold feeding and extracting rounds. The LCP2 recess is MUCH better. I wouldn't complain about it at all.
The next guess is Rick's "I'll bet it has something to do with the barrel being able to tilt." This may or may not contribute to the problem, but I think the real source of the problem has to lie within the extractor itself not holding the rim firmly. The spring has been suspected, but a stronger spring was not a fix. So what else could it be?
I think Doc provided the smoking gun with this pic:
Compare this extractor with one from my AR7 that uses a similar pivot pin:
Notice the pivot hole is round - just like the pin the extractor pivots around. No problems with it. Sooo....
WHY IS RUGER'S PIVOT HOLE ELONGATED????
I think the extractor is being pulled forward far enough for the extracting, unfired rim to leave the recess and be dropped. That's my guess.