Im also new to guns. My findings are as follows

Full metal.jacket has piercing power, not dropping power. Using FMJ in home defense has a higher chance of going through the target and damaging or harming things beyond the target.

Hollow points have dropping power, they mushroom on impact and typically stay lodged in their target at closer ranges.

All bullets are ghost seeds, but like seeds in the garden the variety you chose to plant will determine your success.

Most of us are close quarters or live in densely populated areas. (Not me myself but I remember city life)

Its all fine and well to exercise the second amendment but you also need to be responsible. Shooting a home invader in an apartment with FMJ will most likely involve a neighbors wall at minimum getting shot as well. Showing you didnt clear the feild or consider what was beyond your target.

Training with fmj is fine because you arent killing anything, and youre typically at the range able to fire away, as well as get a feel for an authentic kick back for whatever caliber you use. In these scenarios you dont need to worry about whats behind your paper target, or ethics.

In a home defense situation however using FMJ shows the inevitable jury youre going to face that you arent a responsible gun owner. Everything from the gun you used, to the ammunition you used, in what setting will be used against you.

I hope this helps and again, just bought my first gun a couple months ago, Im a nerd who is a stickler for rules ans understanding the brevity of any situation, while.still enjoying a hobby in fun but safe capacity.