Glock 17, dummy rounds vs. snap caps

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film495

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friend had a Glock 17, was checking it out. I had some 9mm dummy rounds no primer no powder. odd thing was, the dummy rounds worked good to cycle and test mags, but if you dry fired it on one of the rounds it would then jam. snap caps did not produce the same result.

not really familiar with Glocks, what would cause it to Jam when dry firing on a dummy round with no primer? Glock was pretty new, but had a few hundred rounds through it. seemt to function normally, but - we did repeat the same jam sevreral times, so - just curious if that is normal or something needs to be looked into deeper for proper functioning.
 
A number of things might do that.
Case length on the dummy might be just long enough to snag.
And snap caps are generally moulded to be just shy of length for better feeding.
Might be just enough "give" in the slide/barrel fit that dropping the striker is skootching things just forward enough.
 
film495 said:
friend had a Glock 17, was checking it out. I had some 9mm dummy rounds no primer no powder. odd thing was, the dummy rounds worked good to cycle and test mags, but if you dry fired it on one of the rounds it would then jam. snap caps did not produce the same result.
Click to expand...
I have some of the Glock brand dummy rounds and they function perfectly in several 9mm Glocks, Sigs and Berettas. That doesn't mean they will in yours. If the 9mm dummy rounds were once fired brass with a bullet reseated........that may be the issue. They aren't fully resized.

BTW.......when making dummy rounds from fired cases.....drill a hole through both sides of the case. Applying bright paint to the bullet or case head helps in IDing that they arent live rounds.

not really familiar with Glocks, what would cause it to Jam when dry firing on a dummy round with no primer?
Click to expand...
Nothing for Glock that wouldn't apply to every semi automatic. New cases, when fired, "fire form" to the chamber dimensions of that firearm. Fail to resize the case and you have a slightly larger case than unfired brass.


Glock was pretty new, but had a few hundred rounds through it. seemt to function normally, but - we did repeat the same jam sevreral times, so - just curious if that is normal or something needs to be looked into deeper for proper functioning.
Click to expand...
Since it works with your snap cap its likely the dummy, not the gun.
 
What do you mean it jammed after dry firing a dummy round? The gun would just go click, then you would manually cycle in a round, and that round would not fully chamber? The trigger was dead? What is your exact issue?
 
the rounds will fully cycle in my Beretta 92 and the Glock 17. Several loaded mags all the rounds cycle fine. They are once fired brass the were resized, went throught the entire process to become live rounds, simply with no primer and no powder charge; all the measurements and specs are correct on the dummy rounds.

The only difference is if the trigger is pulled on a dummy round, then the Glock would fail to eject and jam. It seemed to do this consistently, so - not sure if that is something specific to a Glock 17, or possibly my friend was just being to delicate with the slide - and the difference was a hitch when it would have a bit more resistance pulling the slide back cause it would have to reset the striker or hammer or whatever is in there, has to be reset. It was just odd, I watched this - but not being my firearm I didn't test this myself, my guess was either that's just a nuance of how a glock works, or he was babying the slide a bit and not racking it quickly and fully after dry firing on the dummy round.
 
So the dummy rounds won’t manually eject, like they missed extractor? As long as the pistol cycles live ammo, I wouldn't worry about it. Use what works on your clearing drills:)
 
JDGray said:
So the dummy rounds won’t manually eject, like they missed extractor? As long as the pistol cycles live ammo, I wouldn't worry about it. Use what works on your clearing drills:)
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No, they will manually eject.
 
Normal function.

1. Slide begins to retract.
2. The extractor is hooked over the right side of the cartridge rim and the slide action pulls the cartridge back out of the chamber.
3. When the slide moves far enough back, the ejector hits the left side of the head of the cartridge and this flips the cartridge out of the ejection port to the right.
4. Slide continues back to full travel, then comes back forward.
5. During forward travel the top round in the magazine is stripped and pushed forward into the chamber.

So what you are saying is that steps 1 & 2 work fine. Step 3 is not working. Step 5 causes a jam because the extracted cartridge is still held on the extractor hook.

Is that right?
 
JohnKSa said:
Normal function.

1. Slide begins to retract.
2. The extractor is hooked over the right side of the cartridge rim and the slide action pulls the cartridge back out of the chamber.
3. When the slide moves far enough back, the ejector hits the left side of the head of the cartridge and this flips the cartridge out of the ejection port to the right.
4. Slide continues back to full travel, then comes back forward.
5. During forward travel the top round in the magazine is stripped and pushed forward into the chamber.

So what you are saying is that steps 1 & 2 work fine. Step 3 is not working. Step 5 causes a jam because the extracted cartridge is still held on the extractor hook.

Is that right?
Click to expand...
only when the trigger has been pulled on a dummy round, yes. did not happen on a snap cap. steps 1-5 work on live rounds, dummy rounds, and snap caps. the only jams were on a dummy round when the trigger was pulled. the round did not eject, and thus jam. the round that is supposed to eject did seem to make it out of the chamber, but not out the ejection port.

Anyone know if a Glock 17 is supposed to exhibit this behavior, as designed? Not sure if this is even a problem to be solved.
 
No, I've never had this trouble with snap caps of various types or with a dummy round. I don't use dummy rounds much--I only have one on hand. It's a case with a fired primer and a seated bullet with no propellant. It works fine either with or without a dryfire first.

The firing pin can remain forward after a dryfire, but I really have a hard time seeing how that could cause any problems.

The ejector should kick the case/cap/dummy/cartridge off the extractor hook. If that's not happening, I would be concerned about the ejector. I don't know why this only happens with dummy rounds and only after a dryfire.
 
Try putting a spent primer in your dummy rounds, maybe the empty hole has something to do with it. Drill a hole through the case so you can find it. Also, I had to stuff paper behind the bullet to prevent setback on the dummy round I made, became an issue after awhile.
 
Sounds like the common flaw in the Glock extractor design.

9mm Glock extractors aren't designed to maintain purchase on the rim of the case after it has been extracted from the chamber. When fired the extracted case "free floats" and is kicked out the ejection port if it has enough momentum to reach the ejector. If not, cases are kicked out by the returning slide kicking the case forward and then having them bounce of the front of the port...this is what causes the famous Glock BTF. You can test this by chambering a round, removing the magazine, and then firing the round...the extracted case falls out the magazine well.

The same thing happens when you dry fire except the case doesn't have enough momentum when contacting the ejector. The reason this is more apparent when you've dry fired is that the additional resistance of cocking the striker causes a momentary pause in the slides travel which allows the case to disengage
 
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film495 said:
......, simply with no primer and no powder charge; all the measurements and specs are correct on the dummy rounds.
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Who taught you to make dummy rounds/snap caps?:D A spent primer is fine, but brother....ya gotta fill that hole! a dap of silicone, a rubber eraser, anything to let your firing pin actual strike something.

Now, I'm confused.
The only difference is if the trigger is pulled on a dummy round, then the Glock would fail to eject and jam.
Click to expand...
vs
film495 said:
No, they will manually eject.
Click to expand...
 
You can test this by chambering a round, removing the magazine, and then firing the round...the extracted case falls out the magazine well.
Click to expand...
I wondered where you were going with your post until I read this.

Yes, without a magazine in place, empties will usually fall out the magwell. The extractor needs the support from the follower or the top round in the magazine to keep the round from slipping down out of contact with it. But with a magazine in place, the extractor does hold the case in place until the ejector hits it. At least in the slow motion footage I have been able to find.
 
I just tried this and the dummy round ejected normally through the top of the ejection port. It didn't matter if a magazine was inserted or not.
Dummy round was a S&B case, 124gr RMR MW and no primer.
Gun was a G34.
 
Otto said:
I just tried this and the dummy round ejected normally through the top of the ejection port. It didn't matter if a magazine was inserted or not.
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You won't get BTF when cycling a dummy round either.

It happens with a fired round...or your G34 hasn't reached to point where it will start dropping cases yet. So are like that within the first 200 rounds, others as they approach 1100. There are band-aids like changing extractors or ejectors. The most reliable "fix" has been the Apex Tactical Failure Resistant Extractor
 
Otto said:
I just tried this and the dummy round ejected normally through the top of the ejection port. It didn't matter if a magazine was inserted or not.
Dummy round was a S&B case, 124gr RMR MW and no primer.
Gun was a G34.
Click to expand...
Another guy who makes dummy rounds, and leaves a big hole?:neener:
 
dogtown tom said:
Who taught you to make dummy rounds/snap caps?:D A spent primer is fine, but brother....ya gotta fill that hole! a dap of silicone, a rubber eraser, anything to let your firing pin actual strike something.
Click to expand...

Cutting up erasers seems tedious to me. So I just plug the flash hole from the inside with a toothpick and fill with a dab of epoxy when I make my own dummies rounds.

film495 said:
he was babying the slide a bit and not racking it quickly and fully after dry firing on the dummy round.
Click to expand...
This is possible. Most semi-autos with static ejectors need that slide speed in order for that extracted case to hit that ejector and make it clear the action. But babbying the slide is fine too. If you don't want to lose your dummy or snap cap round by racking back the slide hard. If the magazine is out, the case will fall out the bottom because it isn't supported. Most polymer semi-autos will do this I believe.
 
helpful information. the dummy rounds were really just made to test feeding and magazines, but my friend started to dry fire on them, and this question came up.
 
film495 said:
. . . but if you dry fired it on one of the rounds it would then jam.
Click to expand...
Specifying that the problem is a "jam" is the equivalent of showing up at your mechanic and telling him, "me car no workee". There are tens or hundreds of conditions that fit that description.

With nothing but what you've said, the first thought I have is that the empty primer pocket is allowing too much forward movement of the firing pin, and it's sticking forward.
 
I've made action-proving dummy rounds, especially for our Gun Safety class.
Drilling holes in the cases is an excellent idea; you don't want any oops.
Moon
 
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