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Off Center Primer Strikes

22K views 30 replies 15 participants last post by  Ib2kwik 
#1 ·
During a range session last week I experienced 4-5 off centered primer strikes with my G27 that caused FTF. I was shooting S&B ammo, 180gr. That day I shot 100 rds total. My gun is stock except for a 3.5lb connector bar that was changed out from day one. After the FTF, I would manually eject the failed round and replace it into the mag, it would re-fire normally, each time. I checked the Recoil Spring using the Glock Field Inspection method of holding the firearm up, pulling the trigger, pulling the slide back and releasing it slowly. The gun easily went into battery. The people at the gun range had no real answers except for maybe the ammo's primers being off. My question is why would would it fire normally a second time.

The same day I was also using a G23 with the same ammo and connector bar modification. I experienced no FTF.

Could a RSA just about to wear out, but still allow the slide to go into battery, cause these intermittent symptoms?

Thanks for your assistance.
 
#3 ·
We're all guessing. Only the OP can actually view the gun and there aren't even photos. That's understandable if one doesn't know what to photograph, however.
I couldn't respond off-line. OP, it appears your messaging/conversation options have you limited.

What I'd do:
-check & double-check SLIDE LOCK to determine if it's been installed backwards (slot to rear).
-detail strip slide and clean out firing pin channel with Q-tips. There should be no oil or debris in channel. It's self-lubing.
-examine and possibly replace firing pin spring. Examine all parts, including the firing pin's tip. I've had damaged firing pins before.
-ensure the firing pin cups are installed correctly and cockeyed. The splits between the two cup halves should NOT be over the end of the firing pin spring.

It's also possible there were some intermittent rounds with high primers in that batch of ammo. The firing pin hits the primer; the primer is not seated all the way; the primer gets seated by the initial hit; the 2nd hit detonates the round correctly.

"FTF" in you case means failure to fire, we're all assuming, vs. failure to feed.
 
#6 ·
Thanks for all the kind responses. I've tried my best to answer all the questions, coloring in my answers. I hope it turns out when the response is posted.

We're all guessing. Only the OP can actually view the gun and there aren't even photos. I should have saved one of the rounds, but as I stated the primer strike instead of being in the middle was off to the side. So unfortunately I have no pictures. Each of the failed rounds fired the second time. That's understandable if one doesn't know what to photograph, however. I couldn't respond off-line. OP, it appears your messaging/conversation options have you limited.

What I'd do:
-check & double-check SLIDE LOCK to determine if it's been installed backwards (slot to rear). I checked the slide lock and the slot is indeed facing backwards.
-detail strip slide and clean out firing pin channel with Q-tips. There should be no oil or debris in channel. It's self-lubing. The firing pin channel is squeaky clean. I can easily hear the firing pin move inside the channel when I shake the pistol.
-examine and possibly replace firing pin spring. Examine all parts, including the firing pin's tip. I've had damaged firing pins before. I have (2) G27's. The other is my wife's and rarely used but I did compare the firing pins and springs from both and they looked as close to exactly the same as I could tell. With my G27, I took the firing pin assembly apart and re-installed the firing pin cups back again just in-case that could be an issue.
-ensure the firing pin cups are installed correctly and cockeyed. Taken apart and re-installed as stated above. The splits between the two cup halves should NOT be over the end of the firing pin spring. I'm not completely sure what this means but my cup halves are seated inside the spring.

It's also possible there were some intermittent rounds with high primers in that batch of ammo. Well, the gun range folks thought that the primers were too low. Frankly, I don't put much faith in those folks. When I talked the the gun range armourer he acted like he never heard of my problem. The The firing pin hits the primer; the primer is not seated all the way; the primer gets seated by the initial hit; the 2nd hit detonates the round correctly. That does make some sense.

"FTF" in you case means failure to fire, You are correct Failure To Fire. What happens is the pistol goes "click", I reseat the Mag, rack the slide, ejecting the off centered primer strike round and then I'm good to go. Well...every time except once, when the next round also failed. we're all assuming, vs. failure to feed.
I hope my answers further assist you in narrowing this down. Thanks again.
 
#5 ·
If the pistol is clean and oiled (not filthy and dry) and ammo within spec, then I might start thinking recoil assembly replacement.
Sometimes if the pistol is out of battery and the firing pin assembly does go forward, the pistol can be knocked into full battery, and hard to tell if it was slightly out of battery at the moment of misfire.
 
#7 ·
I checked the Recoil Spring using the Glock Field Inspection method of holding the firearm up, pulling the trigger, pulling the slide back and releasing it slowly. The gun easily went into battery.
I think you're on the right track, but perhaps it's not the RSA this time. Something else caused a jam, perhaps carbon build-up somewhere. Sorry, I cannot guess what it was.

It's probably not your case, but I had such things happen and traced them down to ammunition. It was one of semi-respectable brands, either S&B or Fiocci. I started shooting WInchester whitebox exclusively and the offset strikes disappeared. I should stress that my Glock is in a different caliber, so this is not exactly applicable, but is something to look into.
 
#8 ·
It's probably not your case, but I had such things happen and traced them down to ammunition. It was one of semi-respectable brands, either S&B or Fiocci. I started shooting WInchester whitebox exclusively and the offset strikes disappeared. I should stress that my Glock is in a different caliber, so this is not exactly applicable, but is something to look into.[/QUOTE] I was shooting S&B that day when I had my problem with my G27. I was also shooting the same ammo in a G23 and had no problems. Go figure?
 
#10 ·
This is an old post, but it is happening to me now on a G21. Seemed to happen when the gun heated up. Off center primer strikes. I have others, all the way from 9mm up that have never done this.

This is my 2nd G21 as I sold the first one I bought for this very reason. Now I have a different G21 that is doing it. I have 7 mags, I took yesterday to the range to see how this one shot and performed. 1st round of 7 mags back to back (91 rnds), 2 off center strikes, 1 failure to return to battery (simple nudge and it was good to go). I stopped shooting long enough to reload all 7 mags, then went at it again. Did this again until I shot the 300 rnds I took with me.

Observations:
1. As the gun heated up I had several more failure to return to battery (maybe 7 in 300 rnds).
2. 2nd round of 7 mags, a couple more off center strikes, out of the first 2 mags, then 1-2 out of every mag after that. One mag I didn't have any off center strikes.
3. 3rd rnd of 7 mags had at least one every mag and some back to back. Return to battery was a problem as well (could be just getting dirty and fouled, from back to back shooting). In addition I had a few fail to fire rnds where it looked like light primer strikes. All FTF rnds fired once retried on the first attempt.

I don't have a pic of the off center rnds, but picture if you can, a strike off center by a whole firing pin dimple, towards the perimeter of the primer. Some looked a bit further than that.

I hand load all my ammunition. Have all my life. I use a single stage press, and hand prime all cases. With the hand primer, I can feel the primer "seat" and then I check the case for high primers by feel. High primers are not a problem with my loads. Not being proud here, it's just a condition I am always aware of. I have other Glocks that I load for as well, G17, G19, G22, G23, G20 and G21. Only the G21 is doing this. I hand load all the ammunition for the others. I also have a 1911A1 that shoots the same loads and have never failed to fire.

On my first G21 I replaced the firing pin spring to the next strongest from factory. It did eliminate the light primer strikes that gun was experiencing, but it still would spit out those off center strikes, maybe not as often.

I have taken the slide completely apart for detail cleaning, including the firing pin channel and the liner inside. All was assembled dry.

Thanks for your time to read this long winded report and for any help or suggestions you may have.

Keith Hawkins
 
#12 ·
Thoughts from a person who doesn't reload.

-Have factory ammo on-hand to use as a "sanity-check" against one's reloaded ammo. Having a .45 ACP 1911 to compare against a G21 doesn't really give enough info to diagnose the G21 as the problem.

-Going to a heavier firing pin spring in the G21 seems to blame the G21 as the problem; or at least, it's tuning the Glock to one's reloads; instead of tuning the ammo to the Glock.

-failures to return to battery on one's Glock could be as simple as needing a new RSA; or having one's SLIDE LOCK in backwards. Use Glock-brand parts for now. Using aftermarket parts at this stage of diagnoses can just confuse things.

-Again, I'm not a reloader, but put one's ego aside regarding one's own reloads and double-check all dimensions/specs to known good factory ammo (or is factory ammo never as good as one's reloads?; or as good as factory, which might be a problem).
 
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#13 ·
As stated previously, off center strikes are caused by the gun not being fully in battery. It can be a weak RSA, it can be ammo related as the rim of the case must slide under the extractor smoothly on feed in (bent/dinged case rims can cause OOB conditions), it can be the shooters grip (riding the slide), it can be an extractor issue (again rim must slide up under the extractor), it can be grim causing the slide to not cycle smoothly, etc.

First check the RSA (see YouTube if unsure how), next eliminate your grip by shooting off handed, next start inspecting the rims of the cases and also plunk test every round in your barrel before heading to the range. Finally start looking at the extractor related stuff.
 
#16 ·
It depends on how far out of battery, but yes, a slight amount of OOB will lead to off center strikes on the primer and failures to ignite. It doesn't take much to cause that, almost not visually perceptible. The barrel hood is moving almost dead vertical in the last little bit of travel into lock up.
interesting....I didn't know that. Yes, that could certainly lead to erratic strikes. Thanks for the info.
 
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#18 ·
Thanks guys for the feedback.

Here is what I have planned for my next outing.

1. Ordered a new firing spring and RSA from midway
2. A common denominator in all this is my ammo. So I’ve bought 150 rnds Winchester white box ammo to fire after it gets warmed up. This is when it seems to get worse.

It is possible that my hand is riding the slide a bit so I’ll watch that next time out. The return to battery was off a good 1/8”! I’ll clean it up real good again before I go out again.

Thanks again guys!
 
#20 ·
As stated previously, off center strikes are caused by the gun not being fully in battery. It can be a weak RSA, it can be ammo related as the rim of the case must slide under the extractor smoothly on feed in (bent/dinged case rims can cause OOB conditions), it can be the shooters grip (riding the slide), it can be an extractor issue (again rim must slide up under the extractor), it can be grim causing the slide to not cycle smoothly, etc.

First check the RSA (see YouTube if unsure how), next eliminate your grip by shooting off handed, next start inspecting the rims of the cases and also plunk test every round in your barrel before heading to the range. Finally start looking at the extractor related stuff.
As usual, the master passes down sound information. I learn something from you almost every time you post.
 
#22 ·
I finally had time to disasssemble the slide last night. It was gunked up. Gun was clean when I got it, but didn’t chk the slide, foiled by appearances.
The firing pin assy was a black oily mess, the extractor button had to be removed with needle nose pliers, gingerly but firmly. The extractor channel was covered with same black oily gunk.
Cleaned everything with q-tips and alcohol, and reassembled dry. Drop of rem oil for the extractor. New springs will be in tomorrow, plan next outing tomorrow or Friday.
 
#23 · (Edited)
You bring up a good point mentioning plunk test.

I do that but not on every one. 1:5 are chkd, as I take a box of 50 and chk 1 from each row of 5. I use Lee’s factory crimp die for crimping and fixing case bulging from the bullet being pressed in, as I learned early on when a bullet got stuck from case bulging.
I chkd the cases and loaded ammo I had for rim irregularities. All looked perfect. No dings, burrs or bent rims.
 
#26 ·
You bring up a good point mentioning plunk test.

I do that but not on every one. 1:5 are chkd, as I take a box of 50 and chk 1 from each row of 5. I use Lee’s factory crimp die for crimping and fixing case bulging from the bullet being pressed in, as I learned early on when a bullet got stuck from case bulging.
I chkd the cases and loaded ammo I had for rim irregularities. All looked perfect. No dings, burrs or bent rims.
Before I compete, carry or go to the range I’m 100% doing A plunk test on my ammo. Whether ammo is reloaded on my (2) Dillon 650’s or factory, 100%.
 
#24 ·
Another observation from last night.
The slide release lever looks like it took an impact at some point, looks bent out a bit from being bent in (a ding mark and missing finish). It’s the only blemish. Is it worth replacing? In operation it seems slightly bound up but works ok.
I had to tap the top pin in also. It had worked it’s way out a bit. Could this contribute to the OOB condition?
 
#28 ·
Another observation from last night.
The slide release lever looks like it took an impact at some point, looks bent out a bit from being bent in (a ding mark and missing finish). It’s the only blemish. Is it worth replacing? In operation it seems slightly bound up but works ok.
I had to tap the top pin in also. It had worked it’s way out a bit. Could this contribute to the OOB condition?
I don't think the top pin caused your OOB, just keep an eye on it during your next session. The slide stop lever should be bound up, so I would probably replace it on general principle and because it is cheap. :)

Finally, there should be no oil in firing pin channel, great that you cleaned it, should be GTG.

Looking forward to hearing how the clean extractor is working after you next session.
 
#25 ·
I bet that top pin coming out is caused by a weak recoil spring allowing the barrel to impact harder on the locking block, jarring the pin out. Maybe replace the pin, and the slide release if its damaged, along with the recoil spring assembly. Then fire away and see how it does.
 
#29 ·
Thanks WW, I appreciate your input. I have plunk tested all the ammo (including the bought Winchester rnds) I intend to test with next outing and all passed. So there is clarity on that issue.

New springs won’t be here until Monday so test session won’t happen until I get that replaced.

I also racked in a few rnds to check the extractor fit and all was as should be. I further chkd all the rims on the test ammo and none were disfigured.

The pin could have been already out of place, as it wasn’t something I chkd before I went the first time with it. But I know it now and will keep my eye on it from now on.

I’ll chk into the slide stop bar but will chk YouTube about replacing it before I attempt it. Just not familiar enough with it.

Again, thank you Sir for your excellent insight.
 
#30 ·
The new springs and the slide lock lever arrived and installed.

Just got back from the test session and no FTF, no off center strikes, no slide locking in place mid mag. 350 rnds.

Not sure what the remedy was, just chalk it up to new springs and a good thorough cleaning.

An old friend I use to work gun shows with came up and I helped him this past weekend. For my efforts and my story about my recent adventures with the G21, he sold me a brand new gen 4 G21 for $300. Now I have 2. Both shot very well.
 
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