GURPS Old West - leaving the hammer down on an empty chamber

[Danimal]

My GURPS Old West sourcebook mentioned that a careful gunman would leave the hammer of a revolver down on an empty chamber to prevent accidental discharge. However, I was never able to find any rule in the book to encourage this practice or penalize loading all six chambers. Was this ever addressed in a later edition?

I invented a house rule to promote leaving the hammer down on an empty chamber, which said that a live round with the hammer left down on it would go off when

1) the wearer rolled a critical failure on a Fast-Draw attempt.

2) the wearer dismounted and failed a DX roll at any appropriate penalties i.e. Shock).

3) the wearer used the Jump skill and failed a DX roll at any appropriate penalties.

4) the wearer fell down, succumbed to Knockdown, or otherwise hit the ground unexpectedly and failed a DX roll at any appropriate penalties.

Never got a chance to test this rule, so I don't know how playable it is. The one Old West game I GM'd, the PCs only loaded five rounds.

[Crakkerjakk]

HT93, Unsafe Revolvers, and HT80, Handling specifically addresses this.

Anytime someone tries to do something besides shoot with an unsafe gun in his hand, (examples given include climbing, driving, and riding a horse) the GM may rule that a failed DX or skill roll results in a accidental discharge, malfunction, or damage to the firearm.

[ClayDowling]

Falls and drops are a major risk as well though. If the hammer isn't on an empty chamber, the firing pin is directly on the primer of a live round. A good sharp blow, like if your horse bucks you, and you've just earned the new nickname "Lefty." Luck roll on a fall, and do be sure to check horsemanship occasionally.

[Kale]

Modern revolvers have a feature in the striking mechanism to prevent this. Ye Olden Day revolvers, however, that hammer is sitting right against the firing pin. Any sharp blow to that hammer get's transmitted through the pin right into the primer on the back of the bullet. Basically use common sense; anything that's likely to cause the hammer to be struck will have a chance of setting off the bullet.