In HS I worked at a local hunting/fishing/ archery shop. I heard a lot. Although I sold guns, I mostly let them sell themselves. I didn't try to spin a tale. Also, in hindsight, I'm not sure it was even legal for me to sell them? 01-03
That said, we would OCCASIONALLY take in used muzzleloaders on trade. More of a favor from the owner to his buddies if they wanted a new muzzeloader.
One day someone came in wanting to look at a used Knight Disk rifle. I'm not sure why, but the ole "pot bellied sales guy" was going to show the guy how the gun worked. He had it in the cleaning/maintenance cradle on top of the glass counter, bore pointing slightly customer side of counter, from being parallel.
A big *BOOM* followed by smoke billowing out, followed immediately from dust and small bits of cinder block wall falling in the floor, and rotating Benchmade knife display on the counter top spinning from the muzzleblast.
Sales guy, in weird, dangerous lapse of judgement had opened the bolt of the gun, not checking the gun (nor was it checked prior to being taken in on trade), and pulled the trigger to show customer how said gun worked. Gun was primed and loaded, and subsequently fired.
The scariest part was where the bullet impacted the fall, the shop owner's 4 year old son had been playing with his friend about 2 minutes prior.