Here is a very sweet running 12 gauge reloading system.  All you need is the consumables and you can make those pricey 2A seeds you like.  It also has the MEC 12g 118 Charge Bar: it throws 1 1/8oz shot and the powder that the MEC tables show. I THINK it is 1 /18oz shot and a certain amount of Red Dot (2 ¾ dram) or Green Dot (about 3 dram).  Other charge bars are avail online from a myriad of distributers and eBay real cheap for any specifics you are looking to do with it.

Check them out on MEC’s website and videos online.  They are a very robust and versatile system that will last many thousands of uses.