If you already have a Mantis Blackbeard kit, you can either buy the Blackbeard X magazine by itself for $175 or send Mantis your current Blackbeard magazine battery for a $50 credit towards the upgrade.  If you want to practice reloads with Blackbeard magazines, I would suggest picking up some magazine bumpers available from Mantis. It would suck to break something by dropping the mags too hard.