SW model 439 SA/DA issues

[ziphead65]

Hi Everyone! I have a SW model 439, original owner, purchased, I think, around 1985/1986. Serial number A816556.

Shot it a lot for a few years, then became a safe queen for a while, back to shooting it a bit now.

I've noticed that the DA/SA feature does not work correctly anymore.....after the first round in DA, next rounds should ALL be in SA as the slide draws the trigger back after each shot. But it doesn't always happen. Sometimes just a series of DA shots, like the slide doesn't lock the trigger back for SA as it should.

Just ordered a new Wolff replacement mainspring and hope that does the trick. Any other ideas or recommendations? Still shoots like a champ, just mostly in DA.

Pics attached.

 

[erikpolcrack]

Don't know what to say other than my 439 (SN806932) has never had even the slightest hiccup. Looks like a sibling of yours, except mine has the fixed rear sight. Mine has ambi- safety as well. I got mine from a military rod & gun club while stationed in Germany in the mid-80s. You mention twice about the trigger not being locked back for SA. What about the hammer? Is it staying fully cocked after the slide cycles? What happens if you cycle the slide with the gun unloaded and without a magazine? The hammer and trigger should both be cocked and ready for SA when you manually cycle the slide.

 

[gmborkovic]

Mr. zip, did you change your brand of ammo?

 

[ACEd]

I assume you have cleaned well and lubricated after taking it out of storage - new recoil spring?

 

[BigBoss3006]

I’d guess its just short stroking. Underpowered ammo maybe, cycling enough to eject and feed but not enough to put the hammer in the SA notch.

When it goes back to DA after firing, is it dropping to half cock or fully down to its resting position?

 

[VASCAR2]

My model 39-2 had very few rounds through it and after firing double action the hammer did not stay cocked but followed the slide forward. I had a Friend who was State Police Armorer look at it. He said it had a bad hammer. He had a used 39 hammer with the small hole in the spur. He replaced the hammer and it hasn’t failed since it was changed in about 1981.

On my 39-2 the hammer would fall and get caught on the half cock notch but I seem to remember the hammer going down to the rested position a time or two before the hammer was replaced.

I figure my original hammer had poor heat treat which caused the premature wear. Hopefully the OP’s pistol just needs hotter ammo. My well used 439 will cycle with some very lightly loaded ammo.

Last time I looked Numerich still had S&W hammer in stock.

I just checked the hammers are still in stock for the 439.


Smith & Wesson Model 439 Parts | Numrich Gun Parts

 

[VASCAR2]

I like looking at the Forum members pictures so here are my S&W autos I carried as a LEO.

Here is a picture of my 39-2 with the early style hammer. My 39-2 was manufactured in 1975 to 1976.





Here is a picture of my well used 439.






Here is a picture of my 5904 where I replaced the grips to the flat back strap.

 

[GaryS]

When was the last time you changed the recoil spring?

 

[Sevens]

I'm curious why there are suggestions for recoil spring? Always a good idea for an old pistol but not seeing how that matters given a pistol that is trying to act DAO.

I would be wondering about sear spring or sear/hammer engagement surfaces.

 

[stansdds]

Could be the sear spring, could very easily be a worn sear and/or SA hammer hook surfaces.

 

[gmborkovic]

Im confused. The OP has a 439 he shot alot and worked perfectly. Put the gun in the safe and now does not function correctly? Right so far?
I was unaware springs deteriorate over years of storage. Is this true?
If so I have a lot of springs to replace.

 

[ispcapt]

Im confused. The OP has a 439 he shot alot and worked perfectly. Put the gun in the safe and now does not function correctly? Right so far?
I was unaware springs deteriorate over years of storage. Is this true?
If so I have a lot of springs to replace.

That's the way I read it too.
What I'd do before swapping out anything is give it a good deep cleaning. If able take it clear down to parts. At the very least soak it and blow it dry.
Could very well be dried up lube and fouling. Clean it, lube it, try it.
Do not use WD-40. The carrier dries over time and leaves a mess.
When trying to fix anything I always start with the cheapest possible fix first before throwing progressively more money.

 

[ACEd]

Im confused. The OP has a 439 he shot alot and worked perfectly. Put the gun in the safe and now does not function correctly? Right so far?
I was unaware springs deteriorate over years of storage. Is this true?
If so I have a lot of springs to replace.

It kinda depends - consider a mag left fully loaded for 10 years - I unload it and follower is super wimpy - I disassemble and compare to a similar mag which has not been loaded - there is about an inch difference - granted this was an M1 Carbine mag and the common fix was to pull spring back to full length.

I would assume it depends on what state its compressed to and strength of material etc. In the case of the fully loaded mag the spring was compressed about 90% of its original length.

In general metal may creep under constant high load as well as cyclic load.

I doubt that a recoil spring or main spring or any unloaded spring would be affected significantly in storage. But obviously a recoil spring changes over time with cycles - so I say if in doubt pull the spring in question and compare to a new spring, (also making sure springs are same number of coils).

 

[ziphead65]

OK....thanks to everyone for all your comments and suggestions. Always enjoy the quick responses on this forum. A few responses from me. First, of course I thoroughly cleaned and lubed my 439 before shooting; ammo was all high quality 124g FMJ; when manually racking the slide everything works as advertised, hammer locks back for single action. So.....I did order a new Wolff main spring and it just arrived yesterday, replaced it easily myself. I have not gotten to a range yet to test it. The package from Midway with the new main spring also came with a new STRIKER spring......hadn't thought of replacing that. Any thoughts??
I will try this out in a couple days and report back. If replacing the main spring doesn't work, guess I might contact Smith and Wesson and see if they would be interested in trying to repair this 1985 relic.
Thanks again to everyone for your input and ideas!!

 

[ziphead65]

I’d guess its just short stroking. Underpowered ammo maybe, cycling enough to eject and feed but not enough to put the hammer in the SA notch.

When it goes back to DA after firing, is it dropping to half cock or fully down to its resting position?

Good question, and I don't know. will have to more closely observe at my next range session. I THINK it is dropping back fully down.......

 

[jsbethel]

I might contact Smith and Wesson and see if they would be interested in trying to repair this 1985 relic.

I would pass on that idea. Send it here - http://smith-wessonforum.com/smith-...en-business.html?highlight=bmcm+open+business

 

[ziphead65]

Good question, and I don't know. will have to more closely observe at my next range session. I THINK it is dropping back fully down.......

So got to the range and put a bunch of rounds through my 439 after installing a new Wolff main spring.....still shoots fine but the slide is not locking the hammer back for SA, AND after close inspection, the hammer is at the half cock position, as opposed to completely flat in the full DA position.

Not sure what this means but I will be discussing with Smith & Wesson on Monday.

Thanks again for all interest and comments on my post.

 

[stansdds]

The half-cock notch is doing its job. The sear is not holding the hammer's full-cock hooks. Could be wear/damage on the sear's engagement surfaces and/or wear/damage on the hammer's full-cock engagement surfaces. Think I already said that, but maybe not.

 

[ziphead65]

OK Thanks!!! Will be talking to S&W for a possible repair. Really like the gun, shoots well and i think will be worth the investment.
Much obliged to everyone!!

 

[ziphead65]

Well...had a chat with S&W about my 439. They gladly offered to send me a preprinted shipping label but said non-warranty repairs were on a 5 MONTH backlog; they recommended I look into a local gunsmith for this repair. So....I left it with a Master Gunsmith who works at my local outdoor shooting range. When I described the issue, they labeled it as "hammer follow".......OK, had never heard of that, but describes the problem precisely. So.....should know in a few days. Hopefully not a difficult fix. Might just need a new sear spring.