You've probably seen George Kelgren's first independently designed firearm system, the Grendel SRT. I wanted to show you the design of it's folding stock and how Zytel magic influenced, and was incorporated into the later Kel-Tec Su-16c.

The stock of the SRT is deployed and locked into place via a signal corkscrew that engages with the rear of the main stock body. The screw is attached to a rubber coated steel wire with a knurled handle. The screw handle is flexable and can be actuated from under the hollow comb. The handle is twisted until it stops. To fold the stock, unscrew, and it swings down and under the action. The stock is retained by tension alone, and forms remotely to it's own body.

The stock of the Charlie model is deployed and locks into place automatically. A latch erects and grabs the stock as it folds outwards. Unfolding and folding is easy. Press down on the button beneath the comb to unlock, and the stock neatly folds under the frame. The stock is held to gun by spring pressure and is deployed again just by pulling. It's cut perfectly to fold and fit around standard capcity usgi mags, both 20 and 30rds. 

The SRT makes for the robust system, having no flex. Charlie is faster, being instantly deployable, compared to the SRT which takes two hands and dedicated time. The Charlie is weaker, but allows the shooting hand full purchase on the pistol grip while the stock is stowed.

Both of these stocks put intended function over ergonomics and tradition. Rightfully so, they were still early examples of the modern lightweight compact sporting rifle.

Kel-Tec Su-16c compared to the Grendel SRT.