Going back to 1896, and Smith & Wesson’s first hand ejector revolver (a .32), the lockwork employed a device to retract the hammer after it hit the primer, (called “rebounding,” and then block the hammer from going forward again until the trigger was pulled. But this block was at the bottom, or “foot” of the hammer, and if the hammer spur was hit a solid enough blow there could be enough spring in the hammer, or the hammer stud, on which the hammer rotated, could shear, after which in theory a primer might be detonated if it was in front of the firing pin.
In 1908 or thereabouts, Colt introduced a positive hammer block, which in addition to their rebounding block added an additional one between the frame and hammer just under the firing pin. That prevented the hammer-mounted firing pin from reaching a primer no matter what. After that S&W danced around a bit. They said they’re guns were safe enough, and during the 1920’s and 30’s added a hammer block of sorts that was mounted in the side plate. But it was delicate and required a sort of spring action to work. Their advertising was carefully worded to avoid calling attention to Colt’s much superior system.
In 1944 someone on a battleship dropped a Victory model, supposedly equipped with the older sideplate-mounted hammer block, from some unknown height and it bounced off of a hardwood deck and went off, killing a sailor.
The Navy demanded that Smith do something, and do it fast. They did so, even though they and not had an opportunity to inspect the possibly defective revolver, or a complete and full report of the circumstances surrounding the accident. In theory, the hammer block in the sideplate should have prevented a discharge, even if the hammer was cocked, which is questionable.
The new S&W block worked like the well-proven Colt one, but was linked to the rebound slide rather then the trigger. They still use it in revolvers today. It can be dropped on the hammer spur with the hammer cocked, and so long as the trigger is not prevented from following down the revolver will not fire. Even if the hammer stud should sear, it still won’t fire.
The chance of a pre-1945 S&W revolver going off accidentally if dropped, or the hammer spur being otherwise hit a hard blow is remote – but more possible then a post-1945 gun. While I enjoy shooting the earlier revolvers I seldom carry one as a weapon, because I have other later guns for this purpose. When I do, and it has happened, I load the cylinder to full capacity. Otherwise I leave the hammer down on an unloaded chamber. Others may do as they will…
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