17 rounds base capacity
+8 rounds with extension.
Hardware can be found here for cheap:
https://moosemodshop.com/products/drum-springs-magazine-hardware
The author remixed this model.
Chamfered and recessed the hole the drum spring clips into on the magazine body.
Changed the follower to better accommodate the drum spring.
Added a channel to the magazine and lug to the follower to provide a stop at the top of travel and improve feeding.
Changed the base plate attachment method to 2 4-40 screws.
Created a ranger base plate.
Created an extension.