[mtstream]

i had a 20 lb spring already so I installed that. It reduced the FTLs but did not eliminate them. So, while replacing the spring is a solution, it is not necessarily the right solution.

Failure to reliably go into battery is the symptom of a problem. What is the problem?

Let's eliminate firing ammo from the equation for now and only use the Return to Battery test (holding the gun upright and slowly working the slide while holding the trigger to the rear).

Forces moving the slide into battery:
RSA spring
Resistance points:
Friction points - including the slide stop
Weight of the slide (gravity)
Firing pin spring via engagement of the drop safety

Allowing the trigger to reset frees the slide to return to battery, though it does not always make it.

Where on the slide does this contact take place? I'd like to inspect, possibly polish it

The trigger reset is helping it finish getting into battery during the test and is normal behavior when a gun has failed. It's not normal (in my limited experience) that the gun stays out of battery after releasing the trigger.

What appears to be stopping it, related to the trigger, is the engagement of the drop safety against the firing pin which brings a little resistance from the firing pin spring into play. The drop safety prevents the firing pin from striking the next round prematurely.

You can see why we would point to the RSA spring if you're failing the return to battery test. It's the core piece being tested and should be the strongest force involved. Springs are critical and they wear out with age and/or use. A weak RSA spring can result in damage to the frame. The force of firing live rounds can cover up a weakening RSA spring.

You identified in the first post that the slide was interfering. In your third post, I assumed the slide was no longer interfering with the new barrel - only because it wasn't specifically stated. Is it still making contact? If so, I would contact the slide mfg as it appears it's may be out of spec.

If it is not making contact anymore, then I would focus on the points where the slide wants to stop during the test, looking for anything that would increase or cause friction - such as the slide stop being a little high, etc.

I shouldn't be writing this so late, so I reserve the right to edit after I've slept

 

[Worn]

If you're having the same problems with a LWD barrel, then I'd suspect the slide is a dud. Where did you get this slide from again?

I purchased one of these, complete with RMR and Tritium suppressor sights. That's documented here -- a less than satisfactory experience. That, combined with this failure to go into battery has soured me on this company.

 

[Worn]

You identified in the first post that the slide was interfering. In your third post, I assumed the slide was no longer interfering with the new barrel - only because it wasn't specifically stated. Is it still making contact? If so, I would contact the slide mfg as it appears it's may be out of spec.

Actually, the resistance I was feeling is the mechanism that charges or cocks the striker. Naturally, that is still there.

There is nothing obviously wrong with the striker/spring assembly. If the recoil spring had been weak, it no longer is. I replaced it with a 20 lb spring. (Standard is 18, correct?)

On the bench, it goes into battery properly. At the range, being fired, it does not.

 

[mtstream]

Actually, the resistance I was feeling is the mechanism that charges or cocks the striker. Naturally, that is still there.

That's the drop safety - technically it's the rear of the trigger bar that is resting on the drop safety shelf but it's a little long to say

There is nothing obviously wrong with the striker/spring assembly. If the recoil spring had been weak, it no longer is. I replaced it with a 20 lb spring. (Standard is 18, correct?)

Glock material doesn't specify the weight. I think I saw 17lbs on someone's site.

On the bench, it goes into battery properly. At the range, being fired, it does not.

A long shot idea - inspect the end of the slide where the RSA makes contact. If its bent or has ever been bent and straightened the circle can appear a little oval. It can cause unexplained behaviors.

Something between your frame and this slide doesn't match (captain obvious, I know, sry). Since your original works I'd be trying to get the reseller to exchange and/or help troubleshoot. Especially since it works on the bench but not during live fire. That'll take a lot of observation to narrow down.

 

[Worn]

That's the drop safety - technically it's the rear of the trigger bar that is resting on the drop safety shelf but it's a little long to say

No, not the drop safety. It's the firing pin, when dropped behind the trigger bar at the slide's rear-most travel, as the slide goes forward again, it has to push the trigger forward while charging or cocking the firing pin against spring pressure. That resistance is always going to be there. I haven't quite figured out what the drop safety is doing while this is going on, but the resistance to which I referred is as just described.

Glock material doesn't specify the weight. I think I saw 17lbs on someone's site.

Whether 17 or 18, the new 20 should have compensated for it, if that had been the problem.

A long shot idea - inspect the end of the slide where the RSA makes contact. If its bent or has ever been bent and straightened the circle can appear a little oval. It can cause unexplained behaviors.

Looks Good As New to me.

Something between your frame and this slide doesn't match (captain obvious, I know, sry). Since your original works I'd be trying to get the reseller to exchange and/or help troubleshoot. Especially since it works on the bench but not during live fire. That'll take a lot of observation to narrow down.

At this point, I'm ready to just buy a gen 3 lower...

 

[mtstream]

No, not the drop safety. It's the firing pin, when dropped behind the trigger bar at the slide's rear-most travel, as the slide goes forward again, it has to push the trigger forward while charging or cocking the firing pin against spring pressure. That resistance is always going to be there. I haven't quite figured out what the drop safety is doing while this is going on, but the resistance to which I referred is as just described.

LOL - we are describing the exact same thing from two different perspectives.

The "drop safety" keeps the firing pin from moving forward (prevents auto fire while out of battery), as well as fully engaging the firing pin spring when the trigger is pulled. When you pull the trigger it "drops" out of the way releasing the firing pin.

 

[Worn]

LOL - we are describing the exact same thing from two different perspectives.

The "drop safety" keeps the firing pin from moving forward (prevents auto fire while out of battery), as well as fully engaging the firing pin spring when the trigger is pulled. When you pull the trigger it "drops" out of the way releasing the firing pin.

I'm pretty sure it's called a "drop" safety because it prevents firing when the gun is dropped. The trigger safety has to move it out of the way, right? In any event, it "drops" upward, pushed by the trigger.

The only thing I can find that is different between the two slides, besides the LCI, is the ramp right next to the drop safety. On the gen 2, it's lower and more or less straight. On the gen 3, it has a change in grade and bevel right at the end.

In the first photo, the gen 2 slide is farther, the gen 3 nearer.

In the second photo, gen 2 is on the left, gen 3 on the right.

Why the difference, I do not know. But that's about the only thing I have not eliminated as a suspect.

 

[mtstream]

I'm pretty sure it's called a "drop" safety because it prevents firing when the gun is dropped. The trigger safety has to move it out of the way, right? In any event, it "drops" upward, pushed by the trigger.

Would it help if I added "Certified Armorer" to my signature? http://us.glock.com/technology/safe-action

The only thing I can find that is different between the two slides, besides the LCI, is the ramp right next to the drop safety. On the gen 2, it's lower and more or less straight. On the gen 3, it has a change in grade and bevel right at the end.

Prior to the Gen4 Glock really didn't have "Gen" versions. Upgrades to parts happened more or less when they happened. To be honest, I never really paid attention to the change in the ramp but I don't see any mention of it in 2014 manual. I interpret that to be Glock didn't consider the change to be material.

It bothers me that you can't get it to fail at the bench. I wish someone who has solved this specific issue before would chime in, I'm troubleshooting blind. My next step would be to work from the perspective that the tolerances with the new slide are less so I would look for things that might work with larger tolerances under fire but fail with smaller. Like checking the frame for cracks - completely strip the frame, put pressure under the pin holes with your thumbs and flex the frame - look for small cracks (may need a magnifying glass or reading glasses). Check the locking block for hairline cracks as well. Both are long shots but it's what you're down to.

Do you think it might be from the round not chambering straight?

 

[Worn]

Oops, I'd always heard the Firing Pin Safety referred to as the Drop Safety. Thought it was just another name for the FP safety. I see now that the Drop Safety is different. Thanks for the education. It's a good day when I can learn something new.

Prior to the Gen4 Glock really didn't have "Gen" versions. Upgrades to parts happened more or less when they happened. To be honest, I never really paid attention to the change in the ramp but I don't see any mention of it in 2014 manual. I interpret that to be Glock didn't consider the change to be material.

The ramp beside the firing pin safety? Yeah, I tested and it is not a wear point. Nothing touches that bottom surface at all in normal operation. Looks like I can rule that out as a suspect along with the RSA.

It bothers me that you can't get it to fail at the bench. I wish someone who has solved this specific issue before would chime in, I'm troubleshooting blind. My next step would be to work from the perspective that the tolerances with the new slide are less so I would look for things that might work with larger tolerances under fire but fail with smaller. Like checking the frame for cracks - completely strip the frame, put pressure under the pin holes with your thumbs and flex the frame - look for small cracks (may need a magnifying glass or reading glasses). Check the locking block for hairline cracks as well. Both are long shots but it's what you're down to.

I don't see much more to do other than inspecting the frame as suggested above. This has a baffle factor of 9.2 on a scale of ten.

Do you think it might be from the round not chambering straight?

Anything's possible, but with two different barrels? And only with this particular slide?

With the old slide I had nearly 100% reliability. Maybe I need to go back to the old slide and see if I still have that 100%. It would be a heckuva coincidence if something on the frame chose the installation of a gen 3 slide as the time it decided to malfunction. As you stated, a close inspection of the frame is needed. I think it needs a field test as well.

 

[Worn]

Well, after a quick trip to the range today, I can report that I fired PMC Bronze 115 gr FMJ, 147 gr FMJ subsonic commercial reloads and 158 gr FMJ Fiocchi subsonic with this problem pistol/slide and had only one stovepipe. NO failures to return to battery. The stovepipe was likely me limp-wristing it.

All this was with the heavier 20 lb spring I installed previously and which reduced but did not eliminate the failures to return to battery. I have a new G19 standard spring on order and will install that when it arrives. We'll see if it works as well as the 20 lb spring.

I shot a few rounds from every magazine I have for my G19 (G18 & G19 mags) just to see if that made a difference. It didn't, though the one stovepipe was with a G18 magazine.

Maybe it just took a while to get the new gen 3 slide broken in. The other day I cycled the slide manually dozens of times. Maybe my teardown of the slide corrected something. I dunno.

Time will tell if this was Just One Of Those Things or will be a recurring problem.

 

[Worn]

... It bothers me that you can't get it to fail at the bench.

Another range trip today. This time with a new standard 18 lb recoil spring, The first two magazines were fine. About 5 rounds into the third mag, it failed to lock up in battery four times in a row, then worked sporadically for the rest of the magazine.

And I think I know why it won't fail on the bench. It's heat related. As the barrel and slide warm up, things get tighter. That's my theory at this time.

On my next trip to the range, I'm going to fire a magazine then give it 20-30 minutes to cool down. Shoot something else in the meantime. Then fire another magazine's worth. And cool down again.

If my heat theory is right, then I should have few or no failures. Of course, it it does prove to be heat related, I still don't know what to do. When warm, exactly where is the interference?

Thoughts?

 

[mtstream]

Heat isn't normally a problem with pistols like it is with rifles. The loads are so different and barrels so short. I can't think of a time where a slide was too hot to touch. If heat is the problem I would think the tolerances would have to already be touching.

If you examine your barrel, especially the oldest one, you'll be able to see anywhere it's been rubbing over time. I'm looking at these points on my oldest gun and trying to decide if they could cause a slide to bind up if the barrel were hot. Other than a very small amount of wear on the top of the chamber, I don't see another edge on edge wear mark. What I mean by that is I see a wear mark on the inside of the slide at the recommended lube location but that's a smooth part of the slide. Same with the hole for the barrel - even though it's an edge it rubs against the side of the barrel (smooth) not another edge it could catch on. For that to go from functioning to bind, I believe it would take an enormous amount of heat to change the barrel.

Wish I could actually say something helpful :-D

Something that just crossed my mind is the type of lubricant used. If it's too thin the heat may cause it to run off creating a dry condition. Have you tried cleaning real good and doing the bench tests with a completely dry gun?

Did it happen with all your magazines or just the one?
Did you try the old barrel/slide combination again?
Start paying close attention to the development of wear marks on the new barrel/slide - this may be like watching paint dry.

 

[Worn]

Heat isn't normally a problem with pistols like it is with rifles. The loads are so different and barrels so short. I can't think of a time where a slide was too hot to touch. If heat is the problem I would think the tolerances would have to already be touching.

Still, when you run several magazines through it in a short time, it does get pretty hot. Yes, normally, that would not be a problem but where it's already tight...

If you examine your barrel, especially the oldest one, you'll be able to see anywhere it's been rubbing over time.

Yes, I've been doing that. It just occurred to me that the front sight screw may be interfering. I see no corresponding rub mark on the barrel though. Still, I painted the head of the front sight screw and will look for any evidence of rubbing after the next range trip.

... For that to go from functioning to bind, I believe it would take an enormous amount of heat to change the barrel.

I don't actually think it is a barrel problem as the older barrel is affected too, in this slide. As I've noted, the barrel / slide lockup is a symptom, not the problem.

Something that just crossed my mind is the type of lubricant used. If it's too thin the heat may cause it to run off creating a dry condition. Have you tried cleaning real good and doing the bench tests with a completely dry gun?

Nope. Always just a thin film of lube, though I have run through several lubricants including a TFE product.

Did it happen with all your magazines or just the one?

Multiple.

Did you try the old barrel/slide combination again?

Yes. Worked fine. Also examined the slide for cracks while in bright sunlight. Used a magnifier. No problems observed.

Getting back to the original problem description. We should not be overlooking the fact that battery is often achieved only after the trigger is reset. I am only guessing here but it appears that in that final bit of slide travel on the way to battery, the firing pin safety is re-engaged by the trigger. When that happens, the final barrel/slide lockup is completed. What would happen if the firing pin safety is sticking?

Bearing this in mind, I decided to look yet again at the firing pin safety. I'd pulled it before for inspection and cleaning and even polished the very end per someone's advice.

This time I polished the entire circumference - the part that actually makes contact with the slide. I thoroughly cleaned its recess in the slide as well. Previously, in order to remove the firing pin safety, after removing the extractor, I'd had to tap the slide against my palm or otherwise encourage it to come out. Now, with the polishing, it just falls out when I turn the slide upright without the extractor in place. Seems to me that that's how it ought to be. That's how it is on the old slide.

So, that's my current theory -- that the firing pin safety was sticking. Here's hoping that the polishing did the trick.

 

[mtstream]

You know, I'm so lost for a reason that all I can say is "give it a try"

Since I can't solve the problem, I will keep adding to the general education (unless you'd prefer I just shut up at this point). :whistling:

The reset of the trigger happens in the rear of the gun. It's the lug from the firing pin making contact with the back of the trigger bar (what I referred to earlier as the drop safety). It then pushes the trigger forward into the reset position.

There are three springs involved: The trigger spring, Firing pin spring and one most people don't realize functions as a spring - the Connector (the bar that can be changed to lighten the trigger). It functions like a leaf spring, which is why it doesn't sit flush against the trigger housing.

So the trigger bar drops, releasing the firing pin and the gun goes bang. The slide comes to the rear - the portion of the slide that angles inward pushes the connector over, releasing the trigger bar. The trigger spring pulls the bar upward, raising the rear of the bar high enough to catch the lug again. Now the forward moving slide causes the firing pin lug to make contact with the rear of the trigger bar. This pushes the bar forward and resets the trigger. The trigger spring, trigger bar, etc. are working against the firing pin spring (this process also compresses the firing pin spring).

If you want to see this, push the little tab on the connector towards the middle of the gun. You'll see the crucifix part of the trigger bar pop up. When the trigger moves forward enough for the connector to snap back in place the trigger is reset and can fire. The trigger safety will engage when the trigger moves a bit further forward.

If you move the trigger far enough forward to engage the trigger safety, put a little forward and downward pressure on the tab that would push the firing pin safety before you pull the trigger. There's pressure on the trigger saftey from the trigger spring without the firing pin spring to offset.

 

[Worn]

You know, I'm so lost for a reason that all I can say is "give it a try"

I did, though it was not as thorough a test as I'd have liked. I forgot to restock my range bag with 9mm and so had only 66 rounds with which to test. I shot all 66 with no failures and I was using a stock 18 lb recoil spring. In the last test, the failures began at round 35 or so. So, 66 without a failure to return to battery is an improvement.

So, I'm encouraged but I will not be confident that the problem was fixed by polishing the firing pin safety until I've put several hundred error-free rounds through my G19 in a single session.

I'd hoped that you would address the question I raised: What would happen if the firing pin safety stuck as the slide was moving forward under recoil spring pressure after a shot? You understand the mechanism better than I. Mechanically, could a sticking firing pin safety cause the failures to return to battery?

 

[mtstream]

could a sticking firing pin safety cause the failures to return to battery?

I don't think so. My initial thought is that if it is sticking hard enough to prevent a return to battery from a live fire, you would really feel a lot of resistance when you attempted to pull the trigger. Maybe more than the 18lbs that the RSA spring was applying to get it into battery.

Second, I wasn't sure that it would even make contact with the trigger bar when the slide was coming back forward. To test this (as best as I can) I measured with calipers the distance between the drop safety and the front edge of the slope of the part that pushes the firing pin safety (no idea what to call it). The distance was 2.031". There's about another .16" in distance between the beginning and top of slope.

I compared that to the distance between the firing pin where the resistance from the spring engaged and the front edge of the firing pin safety. That distance was 1.954"

We do know that there is some load on the firing pin spring by the time the slide is in full battery. That's a tricky measurement (my calipers aren't the greatest either). Working with a gun that is currently failing the bench test, it looks like about .15"

So while it's probably close to touching, I don't think it is. Part of this is based on my conclusion that if the firing pin safety was touching the trigger bar while the slide was retuning to battery, it would be in an "open" position which would defeat one of the most critical safety features. Glock would want to engineer that to be as close as practical without defeating the safety.

 

[Worn]

I don't think [a sticking firing pin safety could stop the slide]. My initial thought is that if it is sticking hard enough to prevent a return to battery from a live fire, you would really feel a lot of resistance when you attempted to pull the trigger. Maybe more than the 18lbs that the RSA spring was applying to get it into battery....

Yeah but... If the FP safety sticks, then maybe the firing pin cannot move as it should. That could bring the slide to a halt, could it not? Pushing it up to fire is one thing but what if it doesn't drop down again? I mean, it has to drop with the assistance of gravity and its teeny spring. Not a lot of resistance needed to stop that little guy, but it could jam up the firing pin movement. And *that* might stop the slide. Yes? No?

 

[mtstream]

When the slide is coming forward the firing pin should not make any contact with the firing pin safety. It's there to block the firing pin in case it were to come forward unintentionally (i.e. the drop safety failed). The contact the firing pin lug makes with the trigger bar (drop safety) will keep the firing pin back from the firing pin safety.

While the firing pin should not be making contact with the firing pin safety - If there are any nicks on the firing pin safety, that would be and indication that it is (evidence of a problem). Given what you've already told me though, if there are nicks, I would think they are in the firing process not the cycle. It sounds like the engagement between the drop safety and firing pin lug is good.

Have you called the company you got the slide from? Did they have any suggestions?

 

[Worn]

I am now more convinced than ever that the problem is heat related.

For those of you just joining the show... I bought a gen 3 slide, milled and equipped with an RMR sight and suppressor sights, to be used on my gen 2 G19. I experienced failures to go to battery. The slide would stop short of full barrel/slide lockup. This was especially so if I had yet to reset the trigger. Upon allowing the trigger to reset, the slide would sometimes, but not always, complete its forward motion.

Having tried my original gen 2 barrel and a new LWD barrel and had the problem with both, even with a 20 lb recoil spring, I got the best results by polishing the firing pin safety. Failures were reduced to just a few, and only after several magazines had been fired, making the gun hot.

I should add that, when I polished the firing pin safety, I also polished the front of the barrel block, right where it locks up with the slide.

Today I fired more rounds down range. I was on my fourth 33-round magazine when the first failure occurred. It was the type where, when I reset the trigger, the slide completed its travel.

I experienced two more such by the time I'd fired about 160 rounds.

I let the gun cool and then fired two more 16-round magazines with no failures. To me, this appears heat related but the problem is lessening as the slide gets broken in.

Today I installed a brand new, unpolished firing pin safety and I'll see how that works the next time I go to the range.

 

[Worn]

Another trip to the range today and only two FTLs in roughly 60 rounds expended. The second one left the slide open quite a way and I got a look inside. This is what I saw. (For some reason, the inserted image below is upside down while the linked version is right side up.)

That's the what. The firing pin is clearly blocking the head of the case so that the round cannot get horizontal and be chambered. Can someone tell me why? What is the firing pin doing that? Why isn't it retracted?

When I removed the round and took off the slide, I pointed it upward and pressed the firing pin safety. The firing pin dropped due to gravity. It does not appear to be binding.

I'm left again with it somehow being trigger related. Recall that often allowing the trigger to reset will permit the slide to complete its lockup. Not this time, of course, but often.

So, I'm thinking that using a gen 3 slide on a gen 2 frame requires changing out something trigger-related in the frame to make them work properly together.

Anyone ever seen this before? Know the cause?