i own the 64-2 do i need to keep an open cylinder under the firing pin while carrying , incase of drop on hammer?

jb,

Welcome.
Your model 64 came from Springfield with a hammer block. Unless that has been removed, load "6-for-sure".

Mike

No. The gun is entirely safe with all "chambers" (not cylinders) loaded. S&W patented that feature back about 1898.

Papa,
Not entirely.
The current hammer block flag came along much later, after ADs were reported with the WWII & earlier actions.
Anything in the swingout DA line made after the late 1940s should have it, anything prior COULD be questionable.
Denis

A little demonstration you can do for yourself to verify the safety block is in place and functioning.

1: VERIFY THE WEAPON IS UNLOADED! (goes without saying, but have to say anyway)
2:Cock the hammer to stage it for single action trigger pull
3:Pull the trigger (dropping the hammer) and hold the trigger in the "fired" position
4:note the position of the hammer and how far down it has fallen.
5:release the trigger all the way, as you release the trigger, you will see the hammer move outward (away from the frame) about 1/8"



Side note: you can also look between the rear of the cylinder and the frame and see the firing pin protruding through the frame and into the cylinder chamber if you hold the trigger all the way back. Upon release of the trigger, you will see the firing pin retract out of sight, and safely out of reach of a would-be loaded chamber....

Another side note: You can do this test pulling the trigger double action as well, but using single action is a little easier..

JB: Welcome to the forum. That was a great question. Thank goodness technology fixed that problem. I cannot imagine having to carry on an empty chamber and load it only when the stuff hit the fan.