Legal ramifications? You're kidding, right? Murder involves the unlawful killing of another person, and you have to be alive to be a "person". When you're in a "Night of the Living Dead" situation, it really doesn't matter. Of course you're much more likely to have your brains eaten by spirochetes or amoebas than by zombies. Legal ramifications?
Or is the Ayoob thing about how you're going to be convicted of murder simply because the gun you used to shoot Badguy had lightened springs, nightsights, an action job, or that you used cartridges with hollow point bullets? Here's an excerpt from "The Deadly Force Seminar": the eight-hundred pound gorilla in the room when your case comes up for trial is going to be the fact that you shot someone and he's either dead or injured as a result. Are you going to pretend you didn't shoot him and hope no one will notice? Do you really think the fact that your handgun is better prepared for defensive use than someone else's is will make a difference?
If you really did murder someone, then such things can be evidence of premeditation. But if (and I can say this confidently for another year, at least, given the demise of those fake "castle doctrine bills) you had a good, legally justifiable or at least excusable reason to shoot, then you're much better off to take the air out of the prosecution's case by asserting the affirmative defense, which always involve the admission of the shooting. I tell people I want clients whom I can put on the witness stand in their own behalf, and who can testify, "You're derned tootin' I shot him! I was right to do so, it was necessary, and here's why..." I want clients who can say they acted lawfully in self defense, defense of others, defense of habitation, or stopping a serious felony in progress. If you're really guilty of murder or malicious wounding, then the best thing is damage control ("plea bargain"). No point in going to trial unless you think you're going to get a better deal from the jury than you will from the prosecutor or need to avoid pleading anything other than "not guilty" (also called a "slow plea") so that your plea can't be used against you in a subsequent civil case.
In either case, the kind of bullets you used are going to be the least of your worries. If you're really only interested in defensive use of the firearm, I'd say use the best equipment you can afford, and be as effective as you can with it. If you don't have a lawful reason to shoot, leave the gun in the holster, don't think about it, don't touch it, and don't talk about it. Otherwise, when necessary, be effective. It's kind of a binary choice, because the law does not provide any middle ground.