I think the strangest / scariest thing I experienced while working at the gun shop was:

We had a non-english speaking (just enough to be 10% functional) customer buy a black powder muzzle loader (45 caliber) and then use a bullet puller to dissemble 45Acp ammunition. He then proceeded to put 50 ROUNDS worth of 45Acp powder down the barrel and patched a 32 caliber ball with a section of underwear elastic. Fortunately for him - he didn't understand that a cap was needed on the nipple to ignite the thing.

On the other hand - we could have cleaned out the shallow end of the gene pool by just handing him a $0.02 cap......