Hammer notch S&W pistols SA/DA

[fireS&W]

The hammer 3rd Generation has three notches. From front to back:

1) Full cock (S/A)
2) Middle ...which is your function?
3) D/A

From double action, it seems the middle notch of the hammer push the drawbar down.

From double action, the gun works the same without the middle notch?

Thank you very much in advance

 

[fireS&W]

The hammer has three notches. From front to back:

1) Full cock (S/A)
2) Middle ...which is your function?
3) D/A

From double action, it seems the middle notch of the hammer push the drawbar down.

From double action, the gun works the same without the middle notch?

Thank you very much in advance

Are there any pistol gunsmith here?

 

[Fastbolt]

I'm not a gunsmith, but in a nutshell ... for 2nd & 3rd gen TDA pistol hammers ...

The top set of hammer notches are the single action notch.

The "middle" set of notches are the first set of double action notches.

The bottom notches are the second set of DA notches (often referred to as the Throw Notch).

There are two sets of corresponding notches in the rear of the drawbar which match up with the two sets of DA notches in the hammer.

As the trigger is pulled rearward the drawbar starts moving forward and the first set of drawbar notches engages first set of hammer DA notches, rotating the hammer rearward, compressing the main spring.

At one point in the hammer's rearward rotation the drawbar's first DA notches clears the hammer's first DA notches and the second set of corresponding hammer & drawbar notches engage and continue rotating the hammer rearward.

The hammer is drawn back by the throw notch until the drawbar cams off the hammer, and the hammer is released to fall forward, propelled by the compressed mainspring, to hit the firing pin.

 

[valkyriekl]

One of the notches is the half-cock notch, designed to 'catch' the hammer if the user decides to not fire while the hammer is being cocked back. It is an additional safety, to keep the hammer from hitting the firing-pin while decocking.

 

[Fastbolt]

One of the notches is the half-cock notch, designed to 'catch' the hammer if the user decides to not fire while the hammer is being cocked back. It is an additional safety, to keep the hammer from hitting the firing-pin while decocking.

The Half-Cock notch was present on the 1st gen TDA pistol hammers (they lacked the firing pin safety plunger feature of later models). A 1st Gen pistol MUST have a 1st gen hammer with a half-cock notch.

The later production TDA pistol hammers lacked the half-cock notch. Using a 1st Gen hammer in a 2nd or 3rd Gen TDA gun will result in an audible click during the trigger stroke as the sear nose skips over the half-cock notch.

FWIW, the 2 different generations of standard DAO pistol hammers only have a pair of notches. The upper notch 'locates' the sear nose, enabling the drawbar to engage the second notch, which is the throw notch. There are some critical differences in the shape of the different generation of DAO hammers.

 

[fireS&W]

Ohh, thank you very much Fastbolt.

And what are the differences between the trigger, hammer & drawbar of the model 952 (which is just single action) with these SA & DA?

 

[Fastbolt]

Ohh, thank you very much Fastbolt.

And what are the differences between the trigger, hammer & drawbar of the model 952 (which is just single action) with these SA & DA?

I've never had occasion to open up a 745/845/945/952 series model, and they haven't been included in the various armorer classes, so I couldn't tell you. Sorry.

My interest in S&W pistols has mostly been confined to their various service-type models (although I have enjoyed some sessions with an older M41 upon occasion ).

 

[fireS&W]

Thank you very much again. I've been reading his post several very interesting and others such as "Marks on SC 340 Cylinder and Frame". I like the way your explained.

Hopefully if there is another phenomenon that has some 952 style pistol only SA

Thank you very much Fastbolt