Converting a 3rd Gen from DA/SA to SAO and back

hammy5150 · Mar 20, 2021

I was looking for ammo in a local gun store earlier today when something else in the consignment section caught my eye - a used 4006 with adjustable sights going for about $800. Now that might sound like a lot to others here but in California you take what you can get and $800 especially in this market is a fair price for a 3rd Gen of any kind. I went to go check it out, it had minimal wear on it and looked in pretty decent shape at first glance, but I quickly found out the trigger wouldn't reset into double action while messing with it. Both the gun store employee and I fumbled around with it for a bit before he checked again and found out the seller had it converted to SAO. That little revelation was enough to snap me out of impulse buy madness and pass on it but it did get me wondering how involved these conversions are. How much effort would it have taken to convert it from DA/SA in the first place and how difficult would it have been to switch it back from SAO to DA/SA?

ISCS Yoda · Mar 20, 2021

I hate to be dense but does SAO mean you have to cock the hammer every time you fire this pistol?

hammy5150 · Mar 20, 2021

ISCS Yoda said:
I hate to be dense but does SAO mean you have to cock the hammer every time you fire this pistol?

It would make it functionally identical to a 1911. Hammer cocked for the first shot and then the slide recoiling would take care of the rest. Which, I'm certainly not against but I just don't think fits a regular 3rd Gen duty gun especially with the slide safety set up the way it is.

ISCS Yoda · Mar 20, 2021

Gotcha. I have no idea why someone would change a TDA 3rd Gen into a 1911 style pistol. It makes no sense to me. I'll be curious to see how someone explains how you would change it back.

Meanwhile, is it designed to be carried cocked and locked? Besides the fact that I dislike that mode of carry it totally defeats the whole purpose of a 3rd Gen decocker, etc. Just curious; I don't blame you for not buying it!

epj · Mar 20, 2021

You could start with it cocked, but it would not be locked. Only way to safely carry would be condition 3. Not ideal for civilian carry.

hammy5150 · Mar 21, 2021

ISCS Yoda said:
Gotcha. I have no idea why someone would change a TDA 3rd Gen into a 1911 style pistol. It makes no sense to me. I'll be curious to see how someone explains how you would change it back.

Meanwhile, is it designed to be carried cocked and locked? Besides the fact that I dislike that mode of carry it totally defeats the whole purpose of a 3rd Gen decocker, etc. Just curious; I don't blame you for not buying it!

I didn't really handle it long enough to really remember the details but I think the decocker would still put the hammer down. It just didn't return the trigger to the double action position. I'm guessing someone decided to bubba his 4006 into a faux-PC range toy since IIRC some of the PC guns have the same setup.

JohnHL · Mar 21, 2021

It would be a very simple procedure to grind the double action notches off a TDA (DA/SA) hammer.

Voila! SAO.

Grind the foot off of the sear release lever and now it can be carried cocked and locked.

Converting back would be reinstalling a TDA hammer (and sear if it was also modified).

Nothing to it, just not sure why.

John

PPCSHOOTER · Mar 21, 2021

IT COULD HAVE BEEN A PERFORMANCE CENTER 4006 . SOME OF THOSE WERE SINGLE ACTION. JP

Ethang · Mar 21, 2021

I did something similar back in the early 90's to my 4506 for IPSC matches. Ground off the hammer drop portion of the lever. Could be carried with the hammer back and the safety on, or could manually lower the hammer and still retain the double action function. I still have that modified lever in my desk drawer someplace. Very simple to do and can be returned to normal in just a few minutes. Did not need to modify the hammer at all.

jjfitch · Mar 21, 2021

Magazine disconnect!!

hammy5150 said:
I was looking for ammo in a local gun store earlier today when something else in the consignment section caught my eye - a used 4006 with adjustable sights going for about $800. Now that might sound like a lot to others here but in California you take what you can get and $800 especially in this market is a fair price for a 3rd Gen of any kind. I went to go check it out, it had minimal wear on it and looked in pretty decent shape at first glance, but I quickly found out the trigger wouldn't reset into double action while messing with it. Both the gun store employee and I fumbled around with it for a bit before he checked again and found out the seller had it converted to SAO. That little revelation was enough to snap me out of impulse buy madness and pass on it but it did get me wondering how involved these conversions are. How much effort would it have taken to convert it from DA/SA in the first place and how difficult would it have been to switch it back from SAO to DA/SA?

When checking function did you have the magazine inserted?

Asking for a friend!

Smiles,

hammy5150 · Mar 21, 2021

jjfitch said:
When checking function did you have the magazine inserted?

Asking for a friend!

Smiles,

A passing employee definitely did ask that while we were trying to figure out what was wrong with it and I can confirm the magazine safety was still installed, and the trigger stayed in the SA position with or without the mag in.

JohnHL said:
It would be a very simple procedure to grind the double action notches off a TDA (DA/SA) hammer.

Voila! SAO.

Grind the foot off of the sear release lever and now it can be carried cocked and locked.

Converting back would be reinstalling a TDA hammer (and sear if it was also modified).

Nothing to it, just not sure why.

John

I figured it would take something like that which I honestly can't be bothered to do on a used $800 gun. If it were more in line with the cheaper end of 3rd Gen surplus outside California I probably would have gone for it anyway.

JohnHL · Mar 21, 2021

Yeah, hammy, I agree with you.

$800 is way too much for a used 4006, unless it has some special provenance, and is about twice my price limit for any guns I have purchased.

Besides, I am a shooter, not a collector.

Combat handguns are my preference and I'll take a Warrior Princess over a Safe Queen any day!

John

Heymatt · Mar 25, 2021

John,
The pic I posted in the for sale section shows a modified third gen hammer with the forward tooth ground flat. Is this what you’re describing?

JohnHL · Mar 25, 2021

This picture?

If you mean the second hammer from the bottom, that is a 2nd gen hammer with the "half-cock notch" ground off so that it mimics a 3rd gen hammer.

To convert a hammer to SAO, grind off the first two notches next to the strut.

To convert a hammer to DAO, grind off the third notch from the strut, and leave the others in place.

John

Heymatt · Mar 25, 2021

Yes, second from the bottom.
It's hard to see in the pic, but it is definitely marked "6906".
So someone took a 3rd gen and modified it to work in a 2nd gen?

JohnHL · Mar 25, 2021

Heymatt said:
Yes, second from the bottom.
It's hard to see in the pic, but it is definitely marked "6906".
So someone took a 3rd gen and modified it to work in a 2nd gen?

No.

Look at the bottom hammer.

The notch on the front of that hammer is the "half-cock" notch.

If you look at the second hammer from the bottom, you can see the angle of the notch and where it has been ground off.

2nd and 3rd gen TDA (DA/SA) hammers are interchangeable.

The addition of the firing pin safety made the half cock safety notch redundant.

Testers did not like the "hitch" in the double action trigger pull caused by the sear dragging across the half cock notch so S&W eliminated it.

John

BAM-BAM · Mar 25, 2021

Not sure how it's SAO......... does the decocker work only as a safety? but does not decock the hammer?

On a 3913 you can add a 5906 hammer ( bottom above) and thumb cock for single action first shot........if that's what you want/need.

Heymatt · Mar 25, 2021

Ok, now I got it. So that would make the bottom three, early hammers and the top one a later version. Thanks for the education!

JohnHL · Mar 25, 2021

Heymatt said:
Ok, now I got it. So that would make the bottom three, early hammers and the top one a later version. Thanks for the education!

Yup! You got it.

Bottom three are early (1st and 2nd gen) "style" with half cock safety notch. (There were no compact, spurless, 1st gen hammers.)

Top hammer is later (3rd gen) "style" w/o half cock notch.

S&W "gen" changes were often more "evolutionary" than "revolutionary", that is to say, when they made changes, they often incorporated older parts until the old stock was used up.

John

Converting a 3rd Gen from DA/SA to SAO and back

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