If it is a justified shooting, then the gun modifications are irrelevant as is type of ammo used. Agreed.
But sometimes you have to get a favorable jury decision before you can breathe a sigh of relief that the shooting was, indeed, justified. You thinking it was justified really doesn't count for much. It's the DA who is going to decide whether to charge you, or the jury which is going to decide whether to convict you.
And juries are swayed by perception — which is why defense attorneys always recommend that their clients wear a coat and tie (even if they have never worn those clothes before in their entire lives). And why prosecuting attorneys always try to drag into the evidentiary record anything that they think will reflect poorly on the defendant.
You are not going to find a case where as a matter of law the defendant was found not guilty even though his pistol was modified. It doesn’t work that way. He is just found “not guilty.” That’s it.
And you also will never know if a jury convicts on facts that we might think amount to a justifiable shooting, but they convicted because the prosecution convinced them that the defendant is a bad guy who deserves what he gets — in part because he intentionally modified his gun to make it a more effective killing tool — and/or used reloads because factory ammo is just not lethal enough. He will just be found “guilty.” And that’s it.
If you conceal carry, you do that in anticipation that you might have to use it. And if you use it, you might end up in front of a jury. Increase your odds of a favorable verdict by using a common type of handgun, unmodified, and factory ammo — preferably the type favored by law enforcement in your area.