If they're new, they should come with a cable or trigger lock. I wrapped the cable lock tightly around the handle of the case and locked it. If it can't be opened, you should be GTG. I would be careful about casually looping the cable around the case, though. Just my opinion.
Edit: this is because I have an SUV, so no trunk...
1) The OP specifically said he had a trunk.
2) The requirement to case or put in a trunk only refers to "Large capacity rifles or shotguns". There is no mention of handguns.
3) Per the law, there are no restricitions on the tr)ansport of UNLOADED handguns.
4) Even if you want to be massWussified, If you have a trunk, no locking container needed.
Trigger or action locks don't help you for transport anyway, so should not even be discussed. The law explicitly states they can go in the trunk or a locking container if you don't have a trunk.
In summary. (Assuming you have a LTC-A) The prudent thing is to just put the guns in the trunk, no additional locks or cases needed, although you would be legal putting them anywhere in the car with no lock or case as long as they are unloaded.
Don
Section 131C. (a) No person carrying a
loaded firearm under a Class A license issued under section 131 or 131F shall carry the same in a vehicle unless such firearm while carried therein is under the direct control of such person. Whoever violates the provisions of this subsection shall be punished by a fine of $500.
(b) No person carrying a firearm under a
Class B license issued under section 131 or 131F shall possess the same in a vehicle unless such weapon is unloaded and contained within the locked trunk of such vehicle or in a locked case or other secure container. Whoever violates the provisions of this subsection shall be punished by a fine of $500.
(c) No person possessing a
large capacity rifle or shotgun under a Class A or Class B license issued under section 131 or 131F shall possess the same in a vehicle unless such weapon is unloaded and contained within the
locked trunk of such vehicle or in a locked case or other secure container. Whoever violates the provisions of this subsection shall be punished by a fine of not less than $500 nor more than $5,000.