From AGM, We have the MP003A. What must be one of, if not the, cheapest spring shotgun currently on the market.
This Single Shot, Spring Powered shotgun is pump operated and comes with its own removable 15 round box magazine. Contructed primarily of ABS with essential structrual elements being metal alongside reinforced nylon internals, it is light but reliable. It does feature some hop adjustment with a Hop Slide on the ejection port but this is more a suggestion compared to the hop adjustment you find on a typical AEG.
Overall, This is a cheap but fun piece, ideal for use at your local CQB Site. People have generally been impressed with the performance you get for the price tag.
Specification:
"Adjustable" Hop
AVG 1 Joule Power
15 Round Detachable Magazine
