We have written this post at least 3 times on our old website as the Blackout caliber developed. While the interest in the Blackout seems to be leveled out at this point, we still received calls to order or ask about the availability of the 300 (AAC) Blackout in our break action barrels, so we figure keeping this information readily available is the best choice. The caliber we have come to chamber as a standard is the 30-221 which is just that – a 221 Rem. opened up to the 30