(2) The firearm is carried by the person directly to or from any
motor vehicle for any lawful purpose and, while carrying the firearm,
the firearm is contained within a locked container.
If someone stopped to eat, or otherwise stopped moving, would not it be argued by the prosecutor therefore that you are no longer carrying it directly to or from a vehicle for the duration that you stopped? If police they read ahead of time on the forum people saying, "Let's go eat a sandwich at place X while carrying concealed in locked cases," does not that give them probable cause, especially if the police know exactly your username, to come and find you with your locked case and demand a search on probable cause that your case contains a firearm in violation of 12025?
It seems like you could have two vehicles at some place, and have one vehicle at the far side and one at the close side, and people could walk back and forth between vehicles, I suppose, and never cease to be traveling directly to and from a vehicle, but it seems that many of the venues where it was previously legal to enjoy an activity while carrying unloaded are now effectively gun free zones. I'd be pleased to be wrong.
Where I see an interesting facet of the law is for openly carried handguns in a locked case.
26389. Section 26350 does not apply to, or affect, the carrying
of an unloaded handgun if the handgun is carried either in the locked
trunk of a motor vehicle or in a locked container.
There is no requirement that firearm must be concealed by such a case where a locked case is required, and 26389 specifically exempts locked cases from the prohibition on open carry. Therefore, it appears that if you had a translucent locked case, that you would still be allowed to open carry and it could not be determined to be concealed by a rational judge, (if such a thing exists in California.) However, I'm not aware of what containers might exist that would allow for unloaded locked container open carry.
26350 also may not apply to the Uberti Buntline, because it has an 18 inch barrel and I doubt it is designed to be interchangeable with a smaller one. Use of common language would describe such a gun as a gigantic handgun, but it is not a handgun under the penal code of CA unless if I am mistaken. I'm not sure if such a gun exists, but technically a gun could be much shorter than the buntline and still be legal. [According to my hasty measurements in Gimp, it looks like the Buntline might be around 24 inches long.] A different firearm could theoretically exist with a barrel 2 inches shorter, and the barrel could be in a configuration where the barrel itself extends very nearly to the rear of the firearm and thus you could have a handgun which is barely over 16 inches long in total length, as opposed to 26 inches in order to meet the criteria for a legal rifle that is not an SBR. Such a gun is only 60% as long as a legal rifle, yet would not be a handgun under the CA penal code.