457 mod to DAO

[mikerjf]

This is an account of something I tried with my 457. Anyone experimenting like this should know what they are doing and employ safety precautions. The writer bears no responsibility for what you do with your gun!

In the Smith and Wesson TDA design, the sear holds the hammer at full-cock during SA firing. During DA the sear does not affect the hammer. In the pre-cock DAO design, the sear holds the hammer partially cocked. In the full-stroke DAO design the sear does not affect the hammer.

The only other function of the sear is alignment of the disconnector. The sear’s slot keeps the disconnector toe from turning to one side or the other.

The disconnector is important for SA because it “disconnects” the trigger from the sear while the action resets, but serves no purpose in DAO firing.

I removed the grips on my 457 and slid the sear pin to the left until the sear fell out. Then I put the pin back in as it is needed to locate the sideplate. Once the sear is out you can reach in with a needle-nose and work out the disconnector. Put the grips back on.

Range trip: The 457 now operates like a full-stoke DAO and works great! Every shot is a DA trigger pull.

There are a couple other changes as a result of this:

1. Rotating the safety lever down no longer disconnects the trigger; the hammer will cycle and fall, but it still works as a safety because the safety body physically blocks the firing pin from the hammer.

2. The magazine safety no longer works, because there is no disconnector for the plunger and lever to press down with and disconnect the trigger. Some people like to disable their magazine safety anyway… just know that with this DAO conversion there is no choice, it is disabled.

After trying DAO you can return the gun to standard TDA operation by replacing the removed parts… nothing was modified.

 

[JohnHL]

Nice work, Mike!

I compliment you on your understanding of the inner workings and inter workings of the parts of the fire control mechanisms of these pistols we like so much.

Yours is a clever solution to the problem S&W must have faced when they chose to build second-strike DAO versions of some of their TDA pistols as opposed to using their partially cocked DAO design.

Eliminating the sear and disconnector would certainly have been less expensive than installing a bespoke hammer which deleted the SA notch.

I can only imagine that the real loss of the magazine safety and the seemingly insignificant loss of the trigger disconnect safety was a "bridge too far" for S&W.

And I say seemingly because to some of those who cannot or will not take the time to understand how these systems operate, the loss of a safety device is a loss of a safety device which MUST be a PUBLIC HAZARD and may not be tolerated!

And even more of a problem if those same ignorant persons are in a position to persuade other non-knowledgeable persons, juries, or judges.

Still, kudos for your resourcefulness and creativity!

John

Oh, and "After while, crocodile!"

 

[KurtC]

You can also remove the safety completely and install a flat firing pin retainer, as used on the DAO TSW models.

 

[mikerjf]

Hoping to find one of those. Could also remove the sear spring and its pin, and the decock lever (replace with washer/spacer?)

 

[JohnHL]

You can also remove the safety completely and install a flat firing pin retainer, as used on the DAO TSW models.

Hoping to find one of those. Could also remove the sear spring and its pin, and the decock lever (replace with washer/spacer?)

There's a whole lot you can do if you want to get creative.

Here's a few pics from my thread: Slenderizing the Slim. A 3914 story (with pictures)

I did a DAO "second strike" conversion, eliminated the manual safety, replaced the slide stop lever, and modified a set of 2nd gen compact grips to slim it down even more.

John

 

[Brian Parrish]

Enjoyed that!

Thanks, John, for the link to the old thread, I very much enjoyed this.
Reminded me of 18DAI whom I often miss around here, gone so soon, gone so suddenly...(sigh).

Kind Regards Always!
BrianD