That extra 100 only brought my total to 150 rounds. I won't end up with 1000 rounds or anything for the .40 on hand, just like to have a solid amount (maybe 300-400) that I can work from. (target practice, etc.)

OK, I get it. See, I'm reading your original post as putting some ammo away for a rainy day. "Stockpiling" to me is NOT the same as having ammo for a day at the range.

Buy a few bricks of .22 ammo. Good for target practice and OK for self defense.

When I go shooting I often shoot at least 50 rounds of .40 S&W, 50 rounds of .223 and several hundred rounds of .22lr. I think you should have at least 200 rounds of .40 S&W/ pistol ammo, 100 rounds of rifle ammo and 2,000 rounds of .22lr. That is my low inventory setting. If I get below those quantities it is time to buy more ammo. This gives you the luxury of time to shop for the best buys. Like many shooters I think you should have a lot of cheap practice ammo and enough quality social ammo. At least enough to fill your magazines in case of a home invasion or car jacking.