There is no law specifying that you cannot have ammo and firearms in the same container or space.
Transporting handguns can be done two ways legally: Unconcealed and unloaded in a holster or openly on the seat or dash. Or in a locked case (no description in the law of what is a locked case). Common sense says a hard case/box with combo or keyed lock, or padlock. I use a small briefcase with a combo lock, and roll one number up.
Generally speaking, great info from Army, but there are a few caveats...
You can't have firearms and ammo for them together in any fashion (unless you have a proper exemption) at the State Capitol, its grounds (and some surronding areas), legislator's offices, etc... Having the two together is defined as loaded. PCs 171c, 171d, 171e
Ditto for Gun Shows - PC 12071.4
For transportation purposes a 'locked case' is indeed defined; but not very well.
12026.1. (c) As used in this section, "locked container" means a secure
container which is fully enclosed and locked by a padlock, key lock,
combination lock, or similar locking device.
12026.2. (d) As used in this section, "locked container" means a secure
container which is fully enclosed and locked by a padlock, keylock,
combination lock, or similar locking device. The term "locked
container" does not include the utility or glove compartment of a
motor vehicle.