Here's my question, I would like to build a round that is the hardest hitting (for self defence), that I can also practice with. My AR has a 1-7 twist 16" barrel. I'm thinking if all I pratice with is 55gr fmj and then there ever came a need to use my rifle for it's intended purpose it may perform completely differant. Can I build a round that won"t " break the bank" that will accomplish this?. I thinking the weight of the bullet would be the most important factor. Thanks in advance for the input.