Recently, Wired Magazine ran an article about just how easy it is for children to break into certain models of gun safes. Their findings are interesting, but not totally surprising. Watch for yourself if you haven't already seen it:
We did our own review of pistol safes here, but more or less comparing features of safes, not attempting to penetrate them as the article describes.
One of the researchers, Marc Weber Tobias, has a variety of other very interesting (but dry) videos describing physical lock security and some of the particular products that are defeated. His YouTube channel is worth a review.