Sorry for taking so freaking long for the photos everyone!
This is (as you can see) with the stock magazine of which it came with.
This is the 100-round extended mag, looks silly but fires forever!
To install the battery, the slide is removed and simply pops off.
Extended mag & regular mag - the standard mag is made of a heavy steel
After a 2-round burst (only had 2 bb's in the mag at the time)