By the time the SHTF, you will be unable to buy ammo anyway. You had better start planning to reload and also start stocking the needed components. So far the Liberals have not started requiring you register the components. You can buy these items over the internet and not have to register your firearm. I have the 556 , the 7.62 x 39 and also plan to get the 6.5 Grendal. I can use the same diameter bullet (.264) for my 6.5 Creedmoor. All the AR15 platform cartridges are too cheap to worry about reloading, except the 6.5 Grendal. I can get cheap steel case for it but I and also use brass case ammo and reload, with out storing too many extra components. The more weapon calibers I have, the greater chance for finding / reloading / scavenging or trading for ammo. I have no interest in the 300 Blackout, as the ammo is too expensive to stock, unless you do reload. Not interested in reloading the 300, the Grendel has much better ballistics. That does not mean the 300 is a bad cartridge, it just does not fit into my plans.