Slide closing when changing mags

[Uncle Alvah]

For the most part, I shoot my 97b at a slow pace. When the mag is empty and the slide locked back, I simply hit the mag release button to drop the empty mag, insert a loaded one, and thumb the slide release.
Today, however, I was practicing quick magazine changes, the first time I've done so since I bought the gun. I'd drop the empty mag(pull it is more accurte, it's not "drop free" modified), insert a loaded mag in the well and smack the base plate with the palm of my hand to seat the new magazine. In every case, when I wacked the base to seat the loaded mag, the slide would unlock and chamber a round. Whenever I firmly seated a new mag with said "wack", I was holding a loaded, cocked and locked handgun, no need to hit the slide release.
When a loaded mag was simply inserted and "tapped"  home, it was necessary to hit the slide release to chamber a round and bring the pistol to ready.
Is this an inertia thing, like dropping a Mini-14 on it's butt with the bolt open and a loaded magazine installed, or is the gun malfunctioning?

[Justice4all]

Nope, not really a malfunction, in fact, I've had this happen on quite a few different auto pistols.

What you're probably experiencing is the slide stop contacting a bullet in the mag causing the slide lock to move upwards and unlock the slide.  This happens as the slide lock has to extend far enough into the frame to be actuated by the magazine follower to lock the slide back after the last shot.  Too far in and it will touch a bullet and sometimes cause the issue your having, or worse, the slide locking back after nearly every shot.  Too short and the slide won't lock back after the last shot.

Look for brass marks on the end of the slide lock.  If they're present, LIGHTLY sand a small amount of material off of the lock where the brass mark is and retry.  

Different manufacturers bullets ogives cause more problems than others.

[Walt-Sherrill]

My GLock 34 does that every time.  Many Glocks do -- with some mags.  

If I could figure out how to make my CZs do it, they'd be doing it, to.  

It is a desirable features, if you shoot competitively, and not a problem, otherwise -- as you end up in exactly the same place you would have ended up, with one less motion on your part.  (If you release the mag, the condition is the same: cocked and ready to fire...)

[Uncle Alvah]

It is, as said, kind of a neat "feature". I can't easily reach the slide release from the grip, so to "aggressively insert" the mag and have the gun go hot is an advantage for the type pratice I was doing.
And just FYI, as far as the bullet ogvile goes, the rounds were standard UMC 230 ball, which is pretty much all I shoot.
I love this gun.

[Old Coastie]

When you really slam the slide home, is the barrel always pointing up? It would be interesting to see if it happens with the barrel horizontal or pointing down.

Good shooting,

Mike

[Uncle Alvah]

Thats a good question, I'll try it later and let you know.
In yesterdays session, the gun was indeed pointed upward at about a 45' angle and canted slightly right to align it, so to speak, with the palm of my left hand coming around/up to seat the mag.

[Justice4all]

Desirable feature?  What, to have your weapon perform a function without your input?  I have to disagree.  What if I want to put a loaded mag into the gun with chambering a round?  And considering how many people I see at the range with their fingers on the triggers as they're handling the guns, I don't agree that this is something you'd want in a gun.  At least not for the non comp type shooter.

Most if not all auto pistols I've seen or played with are specifically designed to NOT do this.  But if you want this neat feature, then just add some material to the end of the slide lock.  Shouldn't be that hard to do.

[Uncle Alvah]

Quote:What if I want to put a loaded mag into the gun with chambering a round?

No problem, just insert the mag and seat it normally. I can't describe the difference in a "tap" and a "wack" obviously, but I've inserted many mags and unless one is "enthustiac" about it, the slide stays in place.
Your points about the potential problems this could cause if the gun is being handled carelessly are well taken and appreciated, of course..

[Walt-Sherrill]

This is NOT a "gun" design issue.

As for actions without my intervention? Mine locks back the slide every time it empties without my intervention...  Except when mag springs are weak.  Not all guns do that, and many do don't it consistently.  Old guns don't do it by design.  (Like some of the oldest Ruger Standard .22s, can't be made to do it.)

And if I wanted to put a loaded mag into the gun without chambering a round, I'd do it by inserting the mag in the mag well AFTER the slide was closed. Doing it any other way will automatically feed a round into the chamber as soon as the slide closes.  

You're free to disagree that this is a desireable feature,
but keep in mind that unless you've put the safety on, the gun is ready to fire immedately after the slide closes, anyway.  That means the same idiots who had their fingers in the trigger guard during loading process will have it there when they release the slide, too.  Your concern about safety, while well-intended, isn't likely to change the outcome.

I suspect the 'problem' we're describing has more to do with magazines, and if you look close enough you'll find one that is slightly different than the rest.  I know from first hand experience that only SOME mags do this on my Glock 34 (and my prior Glock 17) and some don't.  Its not a gun thing, its a "mag" thing.

(Adding extra material to the tip of the slide stop where it is engaged by the follower [on either side] isn't likely to make the slide close automatically.  If anything, its more likely to make it lock open prematurely.  That's one of the fixes for premature slide lock: remove material form the slide stop.)

[Uncle Alvah]

Actually, it seems to be a simple matter of inertia.
With the slide retracted, there are two ways of closing the action, yes/no? Either by way of the slide release or by retracting the slide manually a bit further to the rear with your hand and then releasing it. At least thats the way mine works. With the gun empty, and the slide retracted, a good wack to the bottom of the mag well with the flat of my hand will produce the same result. The slide releases and goes foward into battery.
It is significant I think perhaps that this gun has the factory spring in it. A heavier spring would, I think, require a bit harder wack than the factory spring.

[Walt-Sherrill]

That may explain it with your gun, but it doesn't explain it with other guns.  

It may be that the slide stop spring is weak in your gun, allowing a solid whack to dislodge the stop.  

But in the Glocks I mentioned, it isn't the recoil springs -- its definitely a MAG issue.  And its something that those shooting IDPA using Glock count on.

[Uncle Alvah]

Let me ask this, then. Is my former statement "there are two ways of closing the action, yes/no? Either by way of the slide release or by retracting the slide manually a bit further to the rear with your hand and then releasing it" particular to my gun or do all 97b's function this way?

[Walt-Sherrill]

If I understand what you wrote, that's true of all semi-autos (when slides lock back).

There's much debate about which way is best.  Many advocate the "sling shot" method.

Use the slide release/slide stop, or sling-shot it.  But some guns, don't lock back, and some, like Glocks with special mags, also release when the mag is slammed home.

[Uncle Alvah]

Quote:If I understand what you wrote

It surely seems you do.
I'm referring to the same approach that one would use to close the action on a loaded M1 or Mini-14, the retracting of the bolt handle(in this case) slightly and then releasing it to allow the bolt to travel foward.

[dleong]

Uncle Alvah is correct: the slide releasing when a magazine is forcibly inserted into the pistol is indeed caused by the slide stop's inertia. In other words, when a magazine is slammed in, the pistol jerks upward. Inertia holds the slide stop stationary just long enough for it to move downward relative to the pistol, causing the slide to be released.

A worn surface on the slide stop was causing my 97B to exhibit the exact same problem a few years back. The stop would barely hold the slide back, and would release with the slightest tap to the bottom of the pistol. A quick call to CZ-USA yielded a replacement stop.

Here is an image of the two stops:



The old stop is on the left. You can plainly see that the surface on the peg that holds the slide back has worn to a rounded contour.

Uncle Alvah, what is the condition of the slide stop on your 97B?


DL