I have seen lots of people claim that hand loads will get you in trouble. I guess their logic is that if you're using a handloaded .38 you'll get put in prison for murder by the DA, but if you use your .500 S&W with factory loads you'll get a slap on the back and car fare home.
I've NEVER seen a case that shows this to be true. I've done searches on the internet (which has all knowledge, of course
) and likewise found nothing. No one who claims this has ever been able to produce a case (as has been said earlier)
I think what you have to ask yourself is ... what DA, even in California, is going to try to put the woman in jail who shot the serial murder/rapist because she was using handloaded ammo? Might happen in DC or NY, but then they would try to put he woman away irregardless of ammo.
I think the only time it comes in to play is something like you had a pre-existing relationship with the person you defend yourself against. i.e. a business dispute.
I don't use handloads, but then I don't reload. I have more faith in my premium defense ammo than the cheap reloads I buy at the gunshow for some of my weapons (which have only had 2 FTF's with in about 2000 rounds, BTW).
I suppose if I were a reloader and thought I could put together something better than factory, I would.