All quality JHP ammo, especially the bonded type or solid type such as DPX, penetrate coever just as well as FMJ bullets, sometimes better then.

There is absolutely no reason at all to use FMJ ammo for defense. Having both types of ammo in your magazine is an even worse idea.

As to the post above ref 16" being a minimum acceptable panetration, I would have to ask "who says so?". The FBI minimum is 12"