Hello all, I will be visiting the Bay Area next week and my Father-in-law wanted me to take him to an indoor range. Assuming all firearms will be in a locked container, and unloaded, until I get there, what am I restricted to? i.e. 4th gen glocks, no AR pistols, no AR rifles with the shoulder thing that goes up? I do have 10 round mags for all of my firearms that would normally hold more than 10.

I'd really like him to shoot my .300 blk Pistol, but I'm assuming that's a no no.

Any AR-pistol needs to be ban-compliant.  This means that it must have a 10-round mag (or less, down to a sled for single-shot if desired) that cannot be removed without disassembly of the action (popping the takedown pin and pivoting the action open is sufficient to meet this requirement).  Due to an AR receiver's configuration, there is no way to make it ban-compliant with a detachable mag.  

Other pistols if semi-auto obviously also need to be compliant, but few ordinary handguns come with prohibited features other than threaded barrels.  

Can't import >10rnd mags right now.

AR rifles can't have prohibited features or must use a fixed 10-rnd mag.  Prohibited features include flash suppressors (including some devices that are normally marketed as brakes and the like; if it noticeably reduces flash or redirects it from the shooter's vision, is advertised as having flash suppression capabilities, or was designed with flash suppression in mind, it counts as a flash suppressor); thumbhole stocks; pistol grips; telescoping stocks; folding stocks; forward pistol grips (including AFGs); and grenade or flare launchers (which covers, I believe, both spigot launchers like the A2 , cup launchers, and under-barrel tube launchers).

Rifles do not need to be a locked container if the container is designed to store a firearm.  Pistols do need to be locked up.  No destination requirements or limitations for transporting a pistol in a vehicle, but there are if you're transporting it in another manner, such as on foot (must be going immediately to or from a residence or other private property not open to the public, a shooting range, a shooting area on public land, an FFL, etc.).  Ammo does not need to be locked up, stored separately, or magazines be unloaded.  

California is not a duty to inform State.  In fact, informing LE, or making it obvious that you have guns, is not a good idea, especially in the Bay Area, other more densely populated or Left-leaning areas, or when dealing with CHP (Highway Patrol).  If they have reasonable suspicion, at least, to believe you have guns, they can search your vehicle without probable cause or a warrant to find said firearms and ensure they are unloaded and being transported correctly, and often they will go above and beyond what they are allowed to do (like running serials), and from there who knows what will happen?  Just best to avoid the whole scenario.

Thanks for the info, sounds like my ARs would be deemed noncompliant. Guess I'll just bring wheel guns and my 30.40Krag.
How about a glock in a Micro Roni brace? No prob as long as 10 rnd mag and no threaded barrel?

Thankfully, I will be travelling with my attorney, but will do my best, as always to avoid inviting The Man into my life.