One of the more common mechanical causes for firearms whoopsies is a rifle that "won't stay cocked". This is generally caused by our old pal Danny Dremel the Shadetree Gunsmith deciding that he's going to do a "trigger job" on his buddy's Remchester rifle. Not understanding the proper relationship between the size and angle of various mating surfaces in the rifle's lockwork, the end result is a rifle on which the trigger is pretty much superfluous, since the sear is tripped merely by the force of closing the bolt. Hopefully the defect is discovered before the rifle is loaded, and the problem can be fixed by a gunsmith before anybody has to go to the emergency room, but sometimes life is more exciting than that.
A few years ago, Savage came out with a unit called the "Accu-Trigger", which allowed easy and safe adjustment of the trigger down to ridiculously light pull weights with no danger of the rifle going off as the bolt was closed.
Now, I may have mentioned that I'm not the world's most mechanically-inclined individual. In fact, I couldn't even visualize the working relationship of the trigger mechanism on a 1911, which is probably the simplest trigger/sear/disconnector relationship in the handgun world, until I'd detail-stripped one a few times. So you can imagine that the trigger-within-a-trigger setup on the Savage seemed like pure voodoo to me. At the NRA show, however, Savage had a cool gigantic moving model of the Accu-Trigger setup.
Aah-hah! So that's how it works. Golly, Mister Wizard...