"What about using handloads for defense?"
In my opinion there was a time when this was a more reasonable option, but in today's ammo market there are so many really good factory loads that I don't suggest using handloaded ammunition for defense. My reasons are primarily because not all reloaders are created equal so to speak and in a self-protection scenario, there is no room for ammo-related problems.
Then there is the old bugaboo about being "convicted" if you use handloads and death results. Two prosecutors that I've discussed the matter with advise that so long as the ammunition had not been "poisoned" or used "exploding bullets" or something like that, it really has nothing to do with whether or not the shooting was lawful or not. It should be noted that I'm in Texas and it's a more gun friendly state than some others are. I cannot say that some rogue, anti-gun prosecutor might not try and use it against a person, but for the most part I believe that it would have no bearing on the criminal portion of the aftermath.
The inevitable civil suit is a different matter. I do believe that the use of handloads would be brought up and that the plaintiff's attorney would portray the shooter in the worst possible way. The burden of proof is less in a tort case and the use of handloads might result in defendant not prevailing or having to pay more in damages if he that particular jury was going to find for the plaintiff anyway. While a good attorney can find experts to shoot down the lies that would be spewed, the whole matter could be avoided by not using handloads specifically for self-protection.
In other words, there could be a problem if you loaded up some 9mm JHP rounds and kept the house or carry gun loaded with them when the gun was being used specifically for self-defense. However, let's say that a shooter was at the range shooting targets with a pet small game load or in the hunting field and some crazy person put him into a life-or-death deadly force scenario and winds up shot full of holes with his handloads. In this case, I don't think the ammunition would play nearly as big a part in portraying the shooter as a heartless, bloodthirsty monster. At the same time, it seems to me that ammunition type shouldn't even be an issue. (The legal question should be whether or not the shooting was justified and if so, that should be the end of it from both the criminal and civil aspects. A sure way not to be shot with either handloaded or factory ammunition is simply not to rape, rob, assault, murder and so forth.)
I can easily remember when there were very few choices in JHP ammunition for both 9mm and .45 ACP. Most of those did not expand reliably. Today things are much better and defensive ammunition choices in some calibers are so wide that few if any shops would have all that is available. In those calibers not so often used for self-protection, there are usually at least some choices. I think a person can find a load in the more popular defensive calibers that would meet his perceived needs and ammo requirements. Without sacrificing anything but a few extra dollars, the whole issue can be avoided.
This does not mean that opposing counsel won't try and make an issue of the "dum-dum" bullets used. This is pretty readily discredited when the shooter's firearms expert testifies that the vast majority of police in the US use expanding bullets and goes on to discuss overpenetration issues and safety to others. These topics may be "old hat" to most of us, but will very likely be a "brave new world" for non-shooters on the jury.
In my view, it is unfortunate and a travesty of justice that a person lawfully using deadly force should even have to worry with civil suits following a "righteous shooting." (In Texas, there have been some anti-suit legislation passed for those defending themselves with deadly force, but I am not yet aware of any test cases.) I think they should be immune from civil litigation, but it is what it is and we can avoid some of the headaches by using our handloads just for targets, recreational shooting, and hunting. Having said that, I wouldn't hesitate to use a handload if needed for protection at that instant and it was what was in the gun.