Old 439 - slide won't lock back

[jmace57]

I have a VERY well worn Model 439 that I got from a sheriff's sale a number of years ago.

When it has an empty magazine in it, the slide does not lock back. This is with both factory and aftermarket magazines.

Could it be a worn slide release?

I'd appreciate any suggestions. Many thanks!

Jim

 

[lrrifleman]

OP, since this problem persists with multiple magazines, I'd look at the slide lock/release. How worn is the nub that engages the magazine follower?

 

[JohnHL]

Will the slide lock back manually?

That is, if you pull the slide back manually on an empty mag will the slide lock back?

Does it only happen when firing?

If you hold the slide stop in the up position deliberately, and pull the slide back, will the slide stop hold the slide?

John

 

[jmace57]

John - no. If I am just sitting with an empty mag, and rack the slide, it does not lock back. I CAN move the lever into the detent and it will lock.

I removed the slide lock and slide...then re-installed. It works maybe 1 time in 10 now.

Thanks

 

[armorer951]

If you have ruled out the followers and the magazine springs....check to see if there is space between the lever body and the frame. It's possible that the slide stop or stem is bent.

Also, the slide stop button in the frame is a staked in part, and may be loose, and it may have changed position. The angle on this button must be correct for the slide stop to work properly.

 

[jmace57]

Thanks to all. I have been messing with this, and at APPEARS that it may be binding where this pin is rubbing across the little "nub" on the frame. It feels gritty and not moving smoothly.

 

[armorer951]

Make sure the slide stop button in the frame has not come loose, and is rotating or has rotated. It is staked in the frame.

 

[JohnHL]

That pin (plunger) has a relatively stiff little spring behind it but it should push in and out freely.

It does somewhat "bind" on the frame "nub" but the slide stop should pivot freely up and down with the slide held back.

In operation, the magazine spring must be strong enough to push the follower lip up against the slide stop lever's protrusion.

The follower lip must be in good enough condition to positively interact with the slide stop's protrusion.

The slide stop's protrusion must be in good enough condition to interact positively with the magazine follower.

The slide stop must pivot freely up into the slide notch.

The slide stop hook and slide notch must be in good enough condition that the hook will hold the slide without upward pressure.

That should give you a good trail to follow and I hope it helps.

John

 

[jmace57]

I think you guys may have nailed it.

"In operation, the magazine spring must be strong enough to push the follower lip up against the slide stop lever's protrusion."

I tried the two mags out of my 639, and it worked perfectly. I had the original mag that came with the 439, and had tried a couple of aftermarket mags without success. Not scientific at all, but the springs are definitely stronger in the 639 mags.

 

[JohnHL]

I think you guys may have nailed it.

"In operation, the magazine spring must be strong enough to push the follower lip up against the slide stop lever's protrusion."

I tried the two mags out of my 639, and it worked perfectly. I had the original mag that came with the 439, and had tried a couple of aftermarket mags without success. Not scientific at all, but the springs are definitely stronger in the 639 mags.

Perfect!

Now replace the springs in the troublesome mags with new from S&W or Wolff's (and it wouldn't hurt to replace the followers while you're in there) and it sounds like you will have diagnosed and repaired the problem!

John

 

[stansdds]

Sounds like weak magazine springs.

Now, about those aftermarket magazines. Triple K and ProMag are the two most common aftermarket magazines for the S&W single stack pistols. If yours work, great, but most are unreliable. I have heard of people using the ProMag body and replacing the spring and follower with S&W parts to make them reliable. I do not think I have ever heard of anyone having success with Triple K magazines, most complain that the magazine body is made of poor quality steel and the lips quickly deform.

 

[Racer X]

Since you also have a 639 it seems, order at least a 3 pack of springs from Wolff. I always go with the +10% stiffer on mag springs, because they can go a longer time before replacement. Even a good spring in a 59xx or 69xx magazine isn't strong enough to function properly in my KelTec P-11. It was designed as a backup for police officers, and as such, will take 59xx or 69xx magazines in a pinch. +10% Wolff springs solve the proble. The tiny P-11 slide moves really fast, and if the spring isn't strong enough to lift the round fast enough, you get a missfeed. BAD in any pistol, but even worse in a back-up pistol.

 

[jmace57]

Just a follow up - you guys were right - I bought new magazine springs, and replaced them. It works perfectly now. Thanks again.

 

[Racer X]

Thanks for the follow up.