Since you're not planning to reload, then personally, the only round I'd recommend would be the .223rem. The .204ruger is FAIRLY widely available, but nothing like the .223rem.

Like Sheridan said, if you're planning on using Walmart for all of your ammo needs, then you'll be lucky if they have more than one or two loads in .22-250 or .204ruger, and they may not have these at all. They WILL NOT have .17 Hornet or .17 Fireball. They likely will not have .22 hornet (I have seen it once at walmart). I've never seen 220swift at walmart either.

But every Walmart I've been to has carried 4-5, maybe more loads of .223rem.

None of my local shops carry more than one load of .22 Hornet.

So while I don't agree to limiting myself to "what's on the shelf locally", some people do work this way. Personally, I'd rather order through Midway or roll my own, but it IS nice if you're in a bind and need a box in a hurry that they'd have a load for you on the shelf locally.