For 5.56, I stack Federal M193. Usually from PSA/TargetSportsUSA. (I like 3300+ FPS out of my 20" rifles, 855 don't do it for me)
For 7.62x39, I stack wolf green box from SGammo.
Buy a case or 2 a month, and watch how fast you get a substantial amount of actually useful precious metals stacked up.
That being said, I shoot north of 500 rounds a month on average. So for me, it's a necessity.
It is time...
or....wait for the panic and stay up all night buying the ammo you need for 4x the price it was at yesterday
while maxing out your credit card