From a legal standpoint, in a criminal case, it does not matter. If you are faced with an intruder who, through reasonable perception, you see is armed and you are in reasonable fear of serious bodily injury or death therefrom, it does not matter whether you use a .22 or MAC 10 .45 on full auto. The shooting would be justified. You are not required by law to wound an armed intruder.
The same goes for a wrongful death case in a civil suit. So far as the legal justification for a shooting goes (ie. self-defense), it makes no difference.
Where it may be relevant, is in those cases where "reasonable fear" or "perception" are questionable and not clear. If, because of possible motive or vendetta, the notion of "self-defense" is questionable (such as a case where you shoot someone in your home who you catch screwing your wife and you "thought" he was armed), such a factor could be relevant. But that's it.
However, if were talking strict self-defense against an armed intruder, IT JUST DOES NOT MATTER.