Depends on your state, but in general yes. Just put whatever caliber you are looking for into your favorite search engine (I find Altavista works well on such stuff) and you'll likely find a few dozen places which sell it.
Be warned however that most of them show "out of stock" or "on backorder". I'm waiting on 500 rounds of .233 myself, it did not show either on backorder or out of stock when I ordered it, but a couple of days later the 500 round box did and about a week after that the 1000 round box did. Mine was supposed to have shipped a week ago, but now just shows "on back order, as does my removable AR sights, my 10 AR magazines, and my AR kit. At least I have the stripped lower, and the holographic sight in hand.
Thanks. Would be nice to have some 223. Used to be able to get it easily and cheaply.
I have two AR kits on backorder since early January. Looks like I probably won’t get them until summer.
I ordered a bunch of stripped lowers last year thankfully.