From D&D Wiki
Ammunition Pod [Warfored or construct and MB1-Buster]
Like the Energy Pod the warforged of legand has also seem to have been seen using a container that stored extra ammuntion, these pods were never found but from many accounts and tales similar ones have been made to replicate there affect.
Using the Ammunition Pod
These pods contain the basic ammunition that the BM1-Buster and AM00-Buster use. There is a 15 pod and 25 containers. This will increase the amount you buster can hold, so a 10 + 15 Ammunition Pod will give you 25.If you have to reload your pod and buster cannon it will be a move action even with rapid reload, but if you have a pod already filled you can reload as a free action, granted you have rapid reload. Each pod weights 8lbs and can only have one attached to your Buster at all times. The 15 pod cost 200 gp and the 25 pod cost 400gp. The ammunition is normal cost but it's a belt fed system which adds 10 gp to the total, this also make it faster to reload because both pod and buster autofeed.
Flavor: Rapid Sharpnel Spark "These little pods are great, but remeber to reload before the indicator hits zero. *Wink*"