I did buy this one used and supposed to be unfired so it was bone stock as far as I know!
I thought I might not like the 5mm Evo 2 type of carts, but it's just the opposite. They are easy to clean and load and eject really far! You can see in the video that some of the shells ejected high and far enough to hit my padded wall and bounce back into the video frame.
I haven't fired it a lot yet - the videos were the first chance I got. But it does appear after taking it down to clean and lubricate it that it should be pretty durable for firing as well!