If they successfully stole guns, then they were correct to break in. Guns are one of the most valuable items for burglars to steal. Why the hell were they left in an abandoned house?

Abandoned premises are a whole other thing. If the burglar has no worry that the occupants will return, they may try for more ambitious scores, such as removing the copper water pipes or condenser coils, or ripping up floors, walls, and ceilings looking for hidden caches.