Huh?
If you have or reasonably expect to have kids, buying guns and ammo for those kids is a good idea. However, how do you know what your gun needs are going to be over the next twenty years? What are you going to do, calculate your median or top 5% rate of ammo and gun parts consumption within the last few years, then use that to make projections like "I'll need 10,000 rounds of [caliber] per year; thus, I'll need 200,000 rounds"? Or, "shit, I expect a second Federal assault weapons ban, let me buy 100 80% lowers."
You're trying to game an inherently unpredictable system. Buy what you can, when you can, unless this is a business for you. Even still, businesses have to operate on a profitable basis.