So much nonsense in this thread.
....I was under the impression that disposing/destroying firearms is illegal for civilians, and that the legal way to go about this is to turn them in to LE, where and when the owner will be given a receipt, and the firearm will subsequently be disposed of by the agency, and duly recorded.....
Where did you get that impression?
On the other hand, we have reason to believe that this isn't necessarily entirely accurate:
It's my property...I can destroy it if I want to, right? ....
For example, see post 14. And we know, or should know, that there are all kinds of rules for disposing of various potentially hazardous things like motor oil, all sorts of other chemicals, medical wastes, fluorescent tubes, etc.
At one extreme, simply tossing a working gun in the trash might well violate an applicable safe storage law. Even if there's no applicable safe storage law in a State, one could still have civil liability if someone gets the gun and hurts someone, or criminal liability of a court could find that just throwing a working gun in the trash to be reckless.
At the other extreme, it's hard to see how one could have any liability if he were to reduce his gun to a lump of metal, assuming he had the equipment to do so.
Probably the real question is, "When is a gun sufficiently destroy that it becomes just innocuous trash?" Some guns might be able to be damaged to a considerable extent and still be repairable. Tossing a damaged but repairable gun into the trash might well present the same sorts of legal risks as tossing out a working gun. ATF, for example, provides
guidelines for the proper destruction of machineguns.
And in any case turning an unwanted, junk gun into law enforcement, and getting a receipt will avoid any questions or doubt, and get you off the hook.