calguns.net/calgunforum/showthread.php?t=1305940

What I do also is go in 3 ways with a couple friends for a family annual pass to the ranges. Runs $70 for the year each

There was significantly more in the area you ask about 5-10 years ago.
A large number of such locations are being shut down.
One of the big reasons is the significant amount of trash left behind.
Of those that remain it is often because of volunteer groups that "adopt" the location and go pick up several large truckloads of trash annually.
However even then the trucks that transport the waste are often paid for by government or forestry services, in a state that has a government that is already not particularly fond of firearms.
The volunteers make it significantly cheaper to clean these places up, but typically not free.
So these places still exist, but they are rapidly diminishing in numbers even in remote areas.

Here is alot of good info Jose for open shooting areas near us. calguns.net/calgunforum/showthread.php?t=33126

Well just noticed Lytle creek now charges. lytlecreekrange.com/information/ I'll post more places.

Jose, take the 15 North exit Lytle creek road and head West. another place is in San Gabriel. Take Beach Blvd off the 210 all the way up and there is a open range back there. One more option would be desert areas.

The directions are here with photos. Please confirm it is not restricted. https://californiathroughmylens.com/bonita-falls-lytle-creek