Turners Outdoorsmen is where I used to go, from what I understand they're still open as of a couple months ago. Alot of gunshops have shut down in the last ten years except for the stubborn ones and the big ones.
Fed Ord in El Monte shut down, BB shut down and several of the smaller shops that I used to go to when I lived in Southern California shut down as well.
Turners Outdoorsmen and Lock Stock and Barrel in San Gabriel are the only ones that I know are open.