4006 slide closes when mag is slapped in

[Mod27]

Hey all, my son recently pruchased a used 4006 .40. It's a beautifull gun, I'm extremely fond of all steel handguns.

Anyway, it only came with one magazine, (a S&W 10 round mag) with the blue plastic follower.

When a full mag is inserted in what I consider a normal fashion, with the slide locked back, slipping it in and firmly pushing up with the thumb to latch it- all is well. The slide stays locked back as it should.

But, when he starts it into the mag well and slaps it up with the heel of his hand to latch, it disengages the slide and chambers a round.

It does not do this with an empty magazine, even bashing the floor plate hard with the heel of his hand, the slide stays locked back.

Now, I consider loading a semi auto by slapping the the magazine up into the gun unwise, and I told him so, but anyone know what could be causing this?

Only ammo he has used so far is 180 grain FMJ. I think that it's a mag issue. The slide stop spring seems to have proper tension but IDK, maybe a weak spring could cause this?

But looking for info if anyone else has seen this or heard of it happening.

Thanks!

 

[OKFC05]

All pistols will do this if "slapped" hard enough. Some competitors do it intentionally in matches. When the gun is hit hard enough to "bounce" the slide catch on a loaded mag, there it goes!

 

[fmflorida]

This is completely normal for most weapons. My SIGs and Glocks do the same if you hit them hard enough.

Sometimes it happens, sometimes it doesnt but it isnt anything "wrong" or broken.

If he doesnt want that to happen you can always try putting the mag in softer, just make sure its seated or hold the slide release up as he was doing.

 

[flagman1776]

The slide stop protrudes into the magazine well slightly by design. The empty magazine follower engages the slide stop to hold the slide open. So all is well.
Slapping a loaded mag in... the follower is depressed by the live rounds... there's no pressure on the slide stop. This allows the slide stop to pop free and the slide closes.
Nothing wrong here.

 

[SG-688]

We ran into this with early 4006 pistols. On those at least, the sideplate surface that engages the slide stop plunger was steeply angled - more than prior pistols - apparently designed to push the slide stop firmly clear of the slide. Too steeply so that it was worse than "any pistol will do it."

Oddly, I could not induce this by hitting the butt with my hand but could reliably when firmly inserting a magazine. An abusive slap was not required.

The sideplate can be 'tweaked' or replaced.

Some pistols, the Mauser HSC comes to mind, are designed to do this.

 

[Mod27]

We ran into this with early 4006 pistols. On those at least, the sideplate surface that engages the slide stop plunger was steeply angled - more than prior pistols - apparently designed to push the slide stop firmly clear of the slide. Too steeply so that it was worse than "any pistol will do it."

Oddly, I could not induce this by hitting the butt with my hand but could reliably when firmly inserting a magazine. An abusive slap was not required.

The sideplate can be 'tweaked' or replaced.

Some pistols, the Mauser HSC comes to mind, are designed to do this.

Interesting....I will have a closer look at it now that I know what to look for.

Thanks to all for the informative replies!

 

[Mike in Reedley]

Unless your son is Magnum P.I., there's no reason to slam a magazine in place. In an extreme case the magazine could go past the locked position and wedge deep enough to not allow it to be easily removed and too deep to feed properly.