Almost any decent rifle can go through steel plate pretty easy, you don't even need FMJ ammo. For instance, I have a metal spinning target rated for .44 Magnum. So, I figured a .30-30 wouldn't hurt it. Well at about 75 yards it put a hole in it. These were just regular Winchester Super X. I can't recall correctly, but I want to say its about a 1/2 thick and it spins when shot, still put a hole in it. I'm not really sure what kind of body armor your local criminals have, I don't think any criminals around here are that smart, usually an addict stealing to pay for their habbit. But I would think a decent rifle cartridge would be no match for their home made armor. If you reload, put a FMJ in a .30-30, ought to be decent. A Winchester 94 would be a good affordable option. As would a Remington pump .30-06, which I know someone out there makes fmj ammo for I just can't recall who. A BFR in .30-30 could do the trick as well. But you got to ask yourself a question, if they have armor what exactly are they planning? Are they some idiot thinking with armor on they can't be stopped or are they heavily experienced and intend to have it all out? You may be going up against a professional thief or gunman. Are you up to that? I'm assuming since you are asking this question then you may not be. Perhaps you're better off fortifying your home, just don't make obvious modifications that make them think you have something worth stealing. I don't know if you have a family, but I put mine first. If I thought there was that big of a threat of a gang of armored robbers getting in my house, I would move. It's not worth risking. It doesn't matter how good you are, there's always that chance. Even if you live alone, you can't always protect your house.