Another interesting find down in the depths of the lower floor of Shot Show 2017 is Excel Arms. They make a line of firearms chambered in .22LR, .22WMR and now 5.7x28mm. It uses the Five Seven pistol magazine to feed the blow back system. As you can see below the system is somewhat modular and they offer California compliant models.
The new CX-5.7R California models retail at $874 while the standard AR style is only $795. They are also working on a 9mm version that uses Glock magazines.
Excel Arms also offers a line of Accu-Tek .380 pistols. It is similar in style to the Walther PPK/S. One major difference is the magazine release is a heel catch rather than thumb release.
Stainless models are only $289 while their aluminum framed versions are $324.