The short answer is yes and yes , but the long term reliability is always questionable and in most cases new magazines should be used to replace those that fail to feed properly.
Assuming one knows what they are trying to adjust , magazine feed lips as you refer to, can be tweaked to position the shell in a slightly different approach. Don't forget the follower and spring tension also make a difference. Where new magazines can be readily had, it generaly is a better choice because in many cases the temper of the metal has played a roll in the magazine losing its proper lip angles.