View Full Version : Blown primers and other malfunction troubleshooting
I had some issues yesterday that I don’t understand. Would appreciate any help in getting it sorted out. I’m real bad about diagnosing malfunctions in the moment since I usually just go into immediate action but some of what I recall seems very odd.
Barrel: 12.5 Criterion Core
BCG: Geissele REBCG
Ammo: 56gr 5.56 MEN
Mags: multiple Gen M3 PMAGs and USGI
Buffer: A5 w/ standard rifle spring
Can: KAC 5.56 QDC
Upper’s total round count: 399
The upper was pretty new with only 204 non-suppressed rounds on it before the class. Those rounds were a mixture of cheap brass cases .223 so this was my first time with the MEN in this gun. The malfunctions started towards the end of the day after about 120 rounds. I kept the can on until I started having issues.
First malfunctions were failures to feed from three different mags. It didn’t look super dirty but I initially assumed that was the issue since I had a can so I just added lube and kept going. Then I had a mixture of blown primers and rounds stuck in the chamber. The first primer lodged itself in between a lug in the barrel extension and the case’s rim, so that the round could not be fully chambered. I had to use a knife to pry it out. I then removed the suppressor and within the next mag or two, had another blown primer. I don’t remember the exact reason but the gun just felt weird when cycling so I stopped shooting and looked. The primer was in between the bolt and bolt catch, stopping the BCG basically at the rear of the cycle. This primer was dislodged by pulling the CH back.
The last was an unfired round in the chamber. I don’t remember why I stopped shooting or what even tipped me off about it, but for some reason, the bolt was locked back (I very well may have dropped the mag and locked it to the rear). I do know that I glanced into the chamber and was very surprised to see a round fully seated with no mark on the primer. I let the bolt go (don’t remember if I did this gently or just dropped the bolt catch), pretty sure I pulled the CH with nothing and then dropped the CH and again pulled it and this time the round was extracted.
I know blown primers can be a sign of over gassing but I had the barrel gauged before JT @ RAW assembled it and think it was .068 which seems reasonable. I know MEN is supposed to be hot and based on estimated velocity yesterday, it was, but am surprised by the mix of blown primers and failures to feed.
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We shot a little bit of that MEN with no pressure signs. I'd clean the hell out of the gun and re-assess.
Expect a suppressed carbine-gas 12.5 to dump a lot of fouling into the upper.
A suppressed Colt 633 Commando is filthy after 150 rounds of 5.56 (military or civilian).
I would suspect the Criterion (typically with a tighter Wylde chamber for precision, vice a big, fat, .mil 5.56 chamber) is going to have more "Stiction" and be more sensitive to fouling. A carbine-length gas tube is also going to start un-locking while pressurized with case still obturated against the chamber.
Take a look at Criterion's video at the 2:11 mark and see how much gas is coming back through the chamber on a suppressed rifle (then multiply by five 30-round magazines for 150 rounds. You can see air distortion as high-speed gas bleeds from the vent holes, then the obvious smoke):
https://youtu.be/8axSRCz_tMs?t=131
You walk a tight balance between precision and functioning while fouled with a suppressed Commando. A few remedies are a chrome-lined GI chamber, mid-length gas, a flow-through suppressor, and piston-operation. An XH heavy buffer and maybe an LMT improved carrier might help with cycle timing but offer nothing for handling pressure.
Your cases are holding a lot of pressure and the primers are letting go as peak system pressure is trying to blow them out of the pockets before the bullet un-corks. I can only assume MEN crimps their primer pockets, otherwise you'd lose a bunch more. Check your bolt face for annular gas leakage around the primer pocket crimp. MEN is typically very good ammo.
Good luck.
Ahh.. the good old Wylde Chamber.
I hate to admit it here, but I flat out HATE shooting suppressed ARs. I'm MUCH happier putting on ears and letting my AR breath naturally. With the can everything is dirty. Your brass, your BCG, you air in your face.
constructor
01-17-23, 09:38
Expect a suppressed carbine-gas 12.5 to dump a lot of fouling into the upper.
A suppressed Colt 633 Commando is filthy after 150 rounds of 5.56 (military or civilian).
I would suspect the Criterion (typically with a tighter Wylde chamber for precision, vice a big, fat, .mil 5.56 chamber) is going to have more "Stiction" and be more sensitive to fouling. A carbine-length gas tube is also going to start un-locking while pressurized with case still obturated against the chamber.
Take a look at Criterion's video at the 2:11 mark and see how much gas is coming back through the chamber (then multiply by five 30-round magazines for 150 rounds. You can see air distortion as high-speed gas bleeds from the vent holes, then the obvious smoke):
https://youtu.be/8axSRCz_tMs?t=131
You walk a tight balance between precision and functioning while fouled with a Commando. A few remedies are a chrome-lined GI chamber, mid-length gas, a flow-through suppressor, and piston-operation.
Your cases are holding a lot of pressure and the primers are letting go as peak system pressure is trying to blow them out of the pockets before the bullet un-corks. I can only assume MEN crimps their primer pockets, otherwise you'd lose a bunch more. Check your bolt face for annular gas leakage around the primer pocket crimp. MEN is typically very good ammo.
Good luck.
Wylde chambers (design)are actually larger than a 5.56 chamber, the freebore where the bullet rests is a little shorter.
https://uploads.tapatalk-cdn.com/20230118/bc160f8cf32adb31b862585fe6213517.jpg
https://uploads.tapatalk-cdn.com/20230118/e84cf8a9aa1f7901f2d8b6e2439a0bfa.jpg
https://uploads.tapatalk-cdn.com/20230118/353199e97d238e293636b9a8532ec110.jpg
Quick shots of the BCG. It’s not clean but that should still be functional right? There was a lot of gas blowback in their promo vid which is interesting. I didn’t notice any the entire time except for the first 2-3 rounds right after I dumped lube on it.
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I'm leaning towards the chamber. I don't remember MEN 5.56 being super hot, but those wylde chambers can be an ass ache for sure.
We were estimating that it was moving somewhere around 2800 FPS but didn’t actually chrono it. I don’t know anything about loading but I do know that the MEN doesn’t have crimped primers. Could that be contributing?
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turnburglar
01-18-23, 00:47
We were estimating that it was moving somewhere around 2800 FPS but didn’t actually chrono it. I don’t know anything about loading but I do know that the MEN doesn’t have crimped primers. Could that be contributing?
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100% Blown Primers are an AMMO issue and have nothing to do with the gun.
If you change up ammo I bet you will have no more issues.
Real 556 should have crimped primers, sounds weird yours are not.
100% Blown Primers are an AMMO issue and have nothing to do with the gun.
If you change up ammo I bet you will have no more issues.
Real 556 should have crimped primers, sounds weird yours are not.
I knew it was maybe the most common issue but didn’t think it was 100% the fault of the ammo.
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Crimped primers will help prevent losing primers in your upper, but the problem remains -- your carbine-length gas system with a suppressor is choking itself.
Without gunsmithing I'd first try an XH buffer and an LMT enhanced carrier. You're going to spend some money.
If you want to keep your present overall system length (with the suppressor you already own) you might try a mid-length gas barrel (port pressure will be lower than with a carbine-length, but overall system pressure time until un-corking is the same). It'll help, but won't solve your pressure-time curve issue.
When you clean the bolt keep an eye open for flame cutting around the primer pocket radius on your bolt face:
https://www.ar15.com/media/mediaFiles/18978/bolt_face_jpg-2676485.JPG
I LIKE suppressed ARs, and I like the idea and concept behind them. The mechanics are a challenge, as the rifle-carbine were not originally designed for them.
I doubt it's truly 5.56 pressure ammo. MEN isn't exactly garbage stuff. I'd guess the combo of the Chamber, Gas system, and Suppressor are just not ideal. The powder burn rate in MEN's ammo might be a factor too.
Crimped primers will help prevent losing primers in your upper, but the problem remains -- your carbine-length gas system with a suppressor is choking itself.
Without gunsmithing I'd first try an XH buffer and an LMT enhanced carrier. You're going to spend some money.
If you want to keep your present overall system length (with the suppressor you already own) you might try a mid-length gas barrel (port pressure will be lower than with a carbine-length, but overall system pressure time until un-corking is the same). It'll help, but won't solve your pressure-time curve issue.
When you clean the bolt keep an eye open for flame cutting around the primer pocket radius on your bolt face:
https://www.ar15.com/media/mediaFiles/18978/bolt_face_jpg-2676485.JPG
I LIKE suppressed ARs, and I like the idea and concept behind them. The mechanics are a challenge, as the rifle-carbine were not originally designed for them.
I do have EBCGs in both of my 10.5s so I could easily swap a carrier in to try for a bit. I forgot to check the buffer too but I have one of every weight for spares for the A5 so I could easily drop to A5H0. At this point though I’ll probably keep as is and put some more rounds through it then document the issues better. I have an 11.5 Super Duty and a BCM upper that I need to pour rounds through also so it may just be an expensive trip to the range.
Worst case, I’ll give Criterion a shot at fixing it, otherwise maybe I’ll try out the FCD barrel and see how long a SS lasts. At least I trust their CS.
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It does look pretty crusty but I have run some filthy guns with soft shooting ammo without issue. Clean rinse and repeat with both MEN and other ammo. I think MEN does a decent job on their ammo, kinda surprised. How violent is the ejection / gun when running? Not that it tells you much but it is a data point, especially if its running hot it should run. Unless that brass just hates that W chamber.
PB
It does look pretty crusty but I have run some filthy guns with soft shooting ammo without issue. Clean rinse and repeat with both MEN and other ammo. I think MEN does a decent job on their ammo, kinda surprised. How violent is the ejection / gun when running? Not that it tells you much but it is a data point, especially if its running hot it should run. Unless that brass just hates that W chamber.
PB
I was taking a private precision course so all single shots really, I tend to notice recoil issues more in a string of fire. That said, the recoil didn’t even register until I took the can off. As soon as I did that, I remember being a bit surprised at how much the felt recoil increased.
I may be able to shoot it this weekend, still going back and forth on whether I should clean it first or not. FWIW, it’s better than how most of my ARs normally look. I rarely clean them and usually it’s a non-issue. The can is still a bit new though and this is my first .233 Wylde chamber, plus the only other time I’ve had popped primers was when I was shooting known shit ammo (Freedom Reman) which all adds to why I was stumped.
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That is interesting. I feel more recoil with can on.
Off and it’s silky smooth.
PB
That is interesting. I feel more recoil with can on.
Off and it’s silky smooth.
PB
Which is what everyone says. It was probably just the positional work we were doing that was less stable that happened to coincide with me pulling the can, but it was definitely noticeable.
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I've never heard of a dirty rifle running better than a clean and properly lubed one.
I've used MEN's 7.62x51 ammo, but not their 5.56. If stoppages when using any imported ammo were to occur to one of my previously reliable ARs, the ammo is the first thing I'd change....after properly cleaning and lubing it.
Which is what everyone says. It was probably just the positional work we were doing that was less stable that happened to coincide with me pulling the can, but it was definitely noticeable.
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yea, I guess that falls under all the shit matters huh. Good luck and keep us informed.
PB
BufordTJustice
01-24-23, 22:34
Crimped primers will help prevent losing primers in your upper, but the problem remains -- your carbine-length gas system with a suppressor is choking itself.
Without gunsmithing I'd first try an XH buffer and an LMT enhanced carrier. You're going to spend some money.
If you want to keep your present overall system length (with the suppressor you already own) you might try a mid-length gas barrel (port pressure will be lower than with a carbine-length, but overall system pressure time until un-corking is the same). It'll help, but won't solve your pressure-time curve issue.
When you clean the bolt keep an eye open for flame cutting around the primer pocket radius on your bolt face:
https://www.ar15.com/media/mediaFiles/18978/bolt_face_jpg-2676485.JPG
I LIKE suppressed ARs, and I like the idea and concept behind them. The mechanics are a challenge, as the rifle-carbine were not originally designed for them.
Yep.
Don't rule out adding a Tubbs flatwire AR10 action spring to the above recipe. Yes, the AR10 variant.
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So I intentionally did absolutely nothing and was able to go shoot again. 90 unsuppressed rounds later, it was doing well and then in my last mag of the day, I had a dead trigger. Couldn’t drop the hammer or move the selector to safe so I dropped the mag, racked the CH to expend a live round, and cracked open the receivers. Popped primer under the FCG.
I think I was at 142 rounds for the day, all unsuppressed. The most significant part to me is that this was with different ammo - Igman .223. At this point, I’ve shot at least 500 rounds of that .223 and at least 200 rounds of MEN through other guns and this is the only one to have popped primers seizing the whole thing up. Only one of those was with the can mounted. I’m probably going to email Criterion and see what they think. I’ve heard different things about their CS so we’ll see.
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This is sounding a LOT like a chamber issue. Being essentially a new barrel, I would suggest a good chamber polishing before sending the barrel back to Criterion.
In the meantime, post some pictures of your fired brass if you get a chance. Any other pressure signs?
This is sounding a LOT like a chamber issue. Being essentially a new barrel, I would suggest a good chamber polishing before sending the barrel back to Criterion.
In the meantime, post some pictures of your fired brass if you get a chance. Any other pressure signs?
Forgot to check that. Honestly forgot about trying out one of the E-carriers too. I had to pick up all of the brass though and didn’t notice anything, though most of them were muddy.
ETA - Criterion got back to me within about an hour and asked if I’d headspace’s the bolt and gave me their specs for that. He took the time to talk through some stuff and then also recommended I check gas rings. I appreciate their handling of it so far, now I need to find a gauge that’ll measure to their spec.
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The MEN 5.56 that I have does not have crimped primer pockets so it's reserved for range use only. It will not be replaced, there are options at that price point that I prefer. So far no problem in carbine gassed Colts, unsupressed.
Is it all one batch of ammunition?
Soft brass will also lead to popped primers even with normal chamber pressures . . . .
I've walked this path. I had a double tap and finally my trigger would not break.
Just like you I found a spent primer lodged in the action. I did a lot of head scratching and finally the member A 3E spotted the problem in a pic I posted. I had improperly installed the hammer spring. This resulted in light primer strikes which results in a slow ignition of the powder. This screws up the dwell time with the bolt lock. Because the powder is burning slower when it reaches the gas tube the bolt unlock and chamber pressure are out of synch. This makes the bolt release but the case would stick in the chamber because of the high chamber pressure. Finally the pressure would drop and the case would release and slam into the bolt and/or the primer would blow out.
Inspect an empty case for the witness mark of the bolt face.
I'm thankful A 3E spotted it and kept me from spending more time, money and head scratching.
I could be wrong with my idea but it's worth a look.
I've walked this path. I had a double tap and finally my trigger would not break.
Just like you I found a spent primer lodged in the action. I did a lot of head scratching and finally the member A 3E spotted the problem in a pic I posted. I had improperly installed the hammer spring. This resulted in light primer strikes which results in a slow ignition of the powder. This screws up the dwell time with the bolt lock. Because the powder is burning slower when it
No.
The primer either pops or it does not.
No.
The primer either pops or it does not.
What do you mean by pop? Ignition or falling out?
I forgot to mention I was having too many FTF with light primer strikes. Tried different virgin ammo and no change. When the round did go off I would collect the round, that's when I noticed the image of the bolt face stamped into the case.
I only had a couple of loose primers that actually fell out.
What year was the ammo. Germany stopped production of the ammo when their rifles accuracy went to pot. The bullets had a to thin of a jacket if I remember right. That would be the reason that it was surplus. Germany is not gun friendly and would not release the ammo otherwise. Also the ammo was designed around a gas piston system not a so called Direct Impingement that the AR uses. So the port pressure may be higher when using the ammo. But you would need to see a pressure trace to be able to see what it really is.
My guess, you are over gassed for a suppressor. Or have a weak buffer spring and not enough weight to keep the gun in time.
We blew more primers yesterday that we have blown in the last two years. Mark loaded some 556 ammo with VV N135, the first load was soft so he bumped it slightly then we had collections of primers in our chambers. Mark can post a pic we took. It was crazy.
PB
https://i.imgur.com/Zij7dp5.jpg
Believe the raised ridge surrounding the firing pin indent in the primers indicates a high pressure situation.
Mark
Believe the raised ridge surrounding the firing pin indent in the primers indicates a high pressure situation.
Mark
;) I'll have to explore that idea.
Yes. We always referred to that as “primer flow”, and it is produced by an overpressure situation.
Yes. We always referred to that as “primer flow”, and it is produced by an overpressure situation.
The funny thing is with a Rem 700 factory bolt, I get primer flow with 308 sub sonics. Their firing pin holes are a little large.
The funny thing is with a Rem 700 factory bolt, I get primer flow with 308 sub sonics. Their firing pin holes are a little large.
I've also noticed this.
The load that was light…were its primers cratered like that? You using VV data for 69gr Sierras? With which primers?
The funny thing is with a Rem 700 factory bolt, I get primer flow with 308 sub sonics. Their firing pin holes are a little large.
Of course you’re correct. Oversized FP tunnel can cause that too.
Assumed that wasn’t the case with your AR.
I have heard of folks breaking bolt handles trying to hammer an action open, but have never seen someone twist the bolt body before. You gotta back off a grain or two ;)
Andy
Of course you’re correct. Oversized FP tunnel can cause that too.
Assumed that wasn’t the case with your AR.
We're just running too hot. Velocities don't really show it, but there's not doubt.
If you were running too hot I would expect the primers to be more flattened before you started seeing the cratering around the firing pin.
That and bolt flow marks on the case head.
I know you guys do a ton of reloading and would be able to tell, are any of the cases with primer failure showing loose pockets when you reload them?
I'm still shooting some IMI/Lapua 762x39 fire formed to grendel. The limits of case life are the large rifle primers pockets getting too large. I haven't had primers fall out, but I can tell when I prime with a Lee Auto prime that the tension is very low.
If you were running too hot I would expect the primers to be more flattened before you started seeing the cratering around the firing pin.
That and bolt flow marks on the case head.
I know you guys do a ton of reloading and would be able to tell, are any of the cases with primer failure showing loose pockets when you reload them?
I'm still shooting some IMI/Lapua 762x39 fire formed to grendel. The limits of case life are the large rifle primers pockets getting too large. I haven't had primers fall out, but I can tell when I prime with a Lee Auto prime that the tension is very low.
Do you use the cases with low tension? I have noticed some 5.56/.223 cases with that problem and I just discard them. If I had to buy cases and fire form them I may not be so cavalier about it.
Andy
Do you use the cases with low tension? I have noticed some 5.56/.223 cases with that problem and I just discard them. If I had to buy cases and fire form them I may not be so cavalier about it.
AndyWhen I feel one with low tension while priming I put a sharpie X on the head. Go ahead and plink with it, then retire it.
I have several hundred lapua grendel cases, I just started with IMI 7.62x39 fireformed in 2007-2008 when brass was unobtanium. Some of those are still hanging in there. Primer pocket tension is the life limit, only had a couple of neck splits.
When I feel one with low tension while priming I put a sharpie X on the head. Go ahead and plink with it, then retire it.
I have several hundred lapua grendel cases, I just started with IMI 7.62x39 fireformed in 2007-2008 when brass was unobtanium. Some of those are still hanging in there. Primer pocket tension is the life limit, only had a couple of neck splits.
Mark does the same thing, he draws two circles around the brass and we blast away and he trashes it.
PB
So finally got some Forster headspace gages in and confirmed that was not the issue. I was kind of hoping that it would be so I could move on. Still need to get it out and try it with an E-carrier. I may just replace the whole REBCG with an EBCG and hope that does the trick. I’ve played with my can on my 10.5s the most, both of which have EBCGs and like that setup a lot.
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The funny thing is with a Rem 700 factory bolt, I get primer flow with 308 sub sonics. Their firing pin holes are a little large.
Another thing is if your firing pin spring is weak it can do this too
LMT E-BCG on the way. The Geissele passed head space so I don't know that it'll make a difference but its worth a shot. I also cleaned it and dropped the buffer weight down. Too many variables to know what did it if it works but I'm hoping to use the upper in an LPVO course at the end of the month so I just need it to run.
Alright so I have to check my round count since throwing the E-BCG in and dropping the buffer but so far, no malfunctions due to blown primers. Last weekend, I was using the A5H1 (per Criterion CS) and today I went back to the A5H3.
But.
The BCG is having frequent trouble feeding the first round from USGI mags when I hit the bolt release. I believe I’ve had four of these failures between the last two weeks and I didn’t take note of it at the time, but I believe this was with two different lowers. PMAGs have been a non-issue and I’ve had a few USGI mags that were fine, but every stoppage was with GI mags and none of them were the same mag. The round would just start to feed, so I had to rack it every time.
Also, I noticed a primer that was almost dislodged when picking up brass today. I kept most of the other brass but still need to sort through and see if there are others. No way of knowing if this was the same gun or not since I had several out today, but I’m guessing that it is.
https://uploads.tapatalk-cdn.com/20230325/38e92691c4b447c4a0a38e2bceaa776d.jpg
https://uploads.tapatalk-cdn.com/20230325/076891910c74dab25d3c1e06db1c34c2.jpg
And, as I’m shooting faster, I’m noticing more recoil than I’d expect based on my other guns. I don’t have any other 12.5s but between my 11.5 Geissele and several 14.5s (most with the same flash hider and A5 buffer), this thing kicks a bit. I’ve also noticed that it does spit gas in my face more than I’d expect with the KAC QDC, even with the E-BCG.
Finally, rounds have some zip. I chrono’d it today with the same 56gr MEN at an average of 3099.4 FPS and 77gr S&B at 2633 FPS. For reference, my 14.5 Mod2 KAC was at 2984.8 and 2585.4. All five round groups, taken one after another. Between the recoil and gas to face, I’m only a little surprised that it’s pushing rounds with more FPS than a 14.5 barrel.
Super curious on continued thoughts here. Maybe the chamber is just a tad undersized?
ETA - round count was 541 w/ REBCG and is 886 now so 345 rounds with the E-BCG and no fully blown primers.
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Perhaps I recall incorrectly, but I thought the thing to do is use a heavier buffer when switching to the E-carrier. The E-carrier can be interesting in itself. I have a semi-auto cut E-carrier on the shelf that makes whatever I put it in feel like it has excessive recoil. I also have a normal E-carrier that makes the specific upper it's in feel exceptionally smooth, particularly when used in conjunction with a Tubb flatwire spring.
Perhaps I recall incorrectly, but I thought the thing to do is use a heavier buffer when switching to the E-carrier. The E-carrier can be interesting in itself. I have a semi-auto cut E-carrier on the shelf that makes whatever I put it in feel like it has excessive recoil. I also have a normal E-carrier that makes the specific upper it's in feel exceptionally smooth, particularly when used in conjunction with a Tubb flatwire spring.
Criterion CS wanted me to drop to an A5H1 from the H3 but that was without adding the E-BCG. It was super snappy with that so I went back to the H3. I have two other uppers with E-BCGs, a DD 10.3 and Triarc 105. The Triarc is fine but the DD has always felt buttery smooth.
Also, I noticed a primer that was almost dislodged when picking up brass today.
Lately I see so many casings like this, I no longer even give it a thought. It's just a part of shooting for me now.
Alright so I have to check my round count since throwing the E-BCG in and dropping the buffer but so far, no malfunctions due to blown primers. Last weekend, I was using the A5H1 (per Criterion CS) and today I went back to the A5H3.
But.
The BCG is having frequent trouble feeding the first round from USGI mags when I hit the bolt release. I believe I’ve had four of these failures between the last two weeks and I didn’t take note of it at the time, but I believe this was with two different lowers. PMAGs have been a non-issue and I’ve had a few USGI mags that were fine, but every stoppage was with GI mags and none of them were the same mag. The round would just start to feed, so I had to rack it every time.
Also, I noticed a primer that was almost dislodged when picking up brass today. I kept most of the other brass but still need to sort through and see if there are others. No way of knowing if this was the same gun or not since I had several out today, but I’m guessing that it is.
https://uploads.tapatalk-cdn.com/20230325/38e92691c4b447c4a0a38e2bceaa776d.jpg
https://uploads.tapatalk-cdn.com/20230325/076891910c74dab25d3c1e06db1c34c2.jpg
And, as I’m shooting faster, I’m noticing more recoil than I’d expect based on my other guns. I don’t have any other 12.5s but between my 11.5 Geissele and several 14.5s (most with the same flash hider and A5 buffer), this thing kicks a bit. I’ve also noticed that it does spit gas in my face more than I’d expect with the KAC QDC, even with the E-BCG.
Finally, rounds have some zip. I chrono’d it today with the same 56gr MEN at an average of 3099.4 FPS and 77gr S&B at 2633 FPS. For reference, my 14.5 Mod2 KAC was at 2984.8 and 2585.4. All five round groups, taken one after another. Between the recoil and gas to face, I’m only a little surprised that it’s pushing rounds with more FPS than a 14.5 barrel.
Super curious on continued thoughts here. Maybe the chamber is just a tad undersized?
ETA - round count was 541 w/ REBCG and is 886 now so 345 rounds with the E-BCG and no fully blown primers.
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For your feeding problem, check your feed ramps for a burr using a Q-Tip. Even good barrel manufacturers fail to catch this sometimes, and it kinda grabs the bullet as it goes up the ramp. Just slip some cotton in and around the lug passage on the feed ramps and see if it pulls.
If that’s not it, its the A5H3. 17k and I have noticed this failure to chamber the first round problem with the A5, and for me it seems more common in the heavier ones. He solved it by removing the bias spring in his, but then reverted to a regular setup. I mostly solved it, unintentionally, by using a lighter buffer, and it only does it when I’m not trying to reproduce the problem.
The popped primers are a pressure problem, and it does not appear that swapping buffers or carriers will fix it. Your chrono results confirm this. Be aware that popped primers only occur after the point of plastic deformation of the case head is overcome by pressure, and occurs at a pressure much higher than “max”.
For your feeding problem, check your feed ramps for a burr using a Q-Tip. Even good barrel manufacturers fail to catch this sometimes, and it kinda grabs the bullet as it goes up the ramp. Just slip some cotton in and around the lug passage on the feed ramps and see if it pulls.
If that’s not it, its the A5H3. 17k and I have noticed this failure to chamber the first round problem with the A5, and for me it seems more common in the heavier ones. He solved it by removing the bias spring in his, but then reverted to a regular setup. I mostly solved it, unintentionally, by using a lighter buffer, and it only does it when I’m not trying to reproduce the problem.
The popped primers are a pressure problem, and it does not appear that swapping buffers or carriers will fix it. Your chrono results confirm this. Be aware that popped primers only occur after the point of plastic deformation of the case head is overcome by pressure, and occurs at a pressure much higher than “max”.
Would like to add a data point to the A5 not wanting to chamber phenomenon. I just picked up a brand new A5 built lower that had noticeably more resistance to charging and grittiness than my other 2. I pulled the spring and buffer and lightly coated Slip 2k grease and then EWL 30 on the spring, buffer and as far inside the tube as I could get. After running it manually a dozen times, it became much easier and smoother to run the charging handle.
I wonder if some of the difficulties people have had are related to this. FWIW.
Just went through all of the brass I picked up from yesterday. Without counting, I’m guessing it was about 75% of all the ammo I shot but it was across a lot of different uppers and lowers. Two MEN casings had their primers blown out. One of those was the photo I posted yesterday where the primer was still there but barely hanging on. I also had two odd looking casings from some S&B 77gr that I was testing out.
https://uploads.tapatalk-cdn.com/20230326/8adf48c0d95f8c26fc62db926ed02d69.jpg
The firing pin indent on those primers is noticeable more black than any of the other brass I have. The one on the right is also noticeably raised.
I just sent an update to Criterion, at this point I’m ready for them to take the whole upper and hopefully replace the barrel. I wasn’t planning on putting an E-BCG in this one so while I know it’s likely an upgrade over the REBCG, that was an extra $500 because the upper wasn’t performing how it should. I also have a ton of money invested into the optics for this gun that will just be a paperweight until this is sorted out. Or I’m playing more musical chairs with optics but I’m over that.
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For your feeding problem, check your feed ramps for a burr using a Q-Tip. Even good barrel manufacturers fail to catch this sometimes, and it kinda grabs the bullet as it goes up the ramp. Just slip some cotton in and around the lug passage on the feed ramps and see if it pulls.
If that’s not it, its the A5H3. 17k and I have noticed this failure to chamber the first round problem with the A5, and for me it seems more common in the heavier ones. He solved it by removing the bias spring in his, but then reverted to a regular setup. I mostly solved it, unintentionally, by using a lighter buffer, and it only does it when I’m not trying to reproduce the problem.
The popped primers are a pressure problem, and it does not appear that swapping buffers or carriers will fix it. Your chrono results confirm this. Be aware that popped primers only occur after the point of plastic deformation of the case head is overcome by pressure, and occurs at a pressure much higher than “max”.
Would like to add a data point to the A5 not wanting to chamber phenomenon. I just picked up a brand new A5 built lower that had noticeably more resistance to charging and grittiness than my other 2. I pulled the spring and buffer and lightly coated Slip 2k grease and then EWL 30 on the spring, buffer and as far inside the tube as I could get. After running it manually a dozen times, it became much easier and smoother to run the charging handle.
I wonder if some of the difficulties people have had are related to this. FWIW.
I’ll have to remember to swab the feed ramps when I get home later.
For the A5, the two lowers I’ve been using this on have been tested pretty well and haven’t had issues. One is the most heavily used lower I own and has seen thousands of rounds across multiple 14.5 uppers. The other is newer but was my first SBR lower and so it’s seen at least 1,500 rounds across a DD MK18, Triarc 10.5, and Hodge 12.5 uppers. I don’t remember ever using anything other than A5H3s in either except for the few mags where I was testing the A5H1 recently.
Now all of that said, I do have another new lower that’s had feeding issues with a BCM MK2 14.5. It’s very intermittent but I put the Geissele REBCG in it to see if that helps. The 12.5 has not been on this lower and it does have the A5 system as well but that’s one of my most proven components at this point so I’m unlikely to expect it as the problem for now.
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I goggled the description of your Criterion Core barrel and it comes back Wylde-chambered vice 5.56mm (with the GI throat).
Given it looks like the German MEN ammo may be loaded to CIP or military pressures, I'm wondering if using one of Ned Christiansen's 5.56mm reamers to get you the longer military free-bore might help.
https://i.imgur.com/eD3nZxg.png
I goggled the description of your Criterion barrel and it comes back Wylde-chambered vice 5.56mm (with the GI throat).
Given it looks like the German MEN ammo may be loaded to CIP or military pressures, I'm wondering if using one of Ned Christiansen's 5.56mm reamers to get you the longer military free-bore might help.
https://qph.fs.quoracdn.net/main-qimg-028bdb2e1d9f76b01e7825b545215f27
Yeah it is the only Wylde barrel I have. I know some prefer them but I honestly don’t care about that aspect, I bought it for the barrel profile, gas port size, and reported accuracy from several end users. You already noted the gas blowback in their video and while I thought the .068 was a pretty reasonable size, I did go back to find the current Hodge “large” ports are at 0.0645 so significantly smaller. I’m hoping that it is just an incorrect chamber because I know there are other much larger 12.5s out there but if Criterion won’t take care of it, I have no desire to go through that mess. I’d be more likely to just sell it for a loss with the disclaimer and replace it with a 14.5 Geissele while I wait for them to release a good 12.5 or KAC to come out with their 13.7 and CQB PRT can. I’m not sold on the SLR rail anyways. My BCM rail panels keep peeling off which has never happened on any other rail so I’m thinking their MLOK slots might be a bit over sized.
The good range near me is a four hour round trip so I don’t get to shoot enough to want to spend time dealing with all of this.
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Yes, its a Wylde, but I have not had this problem with my 12.5” Core (yet), or any other Wylde.
One More Time
03-26-23, 11:43
As I understand it, the .223 Wylde chamber is based off of 5.56 NATO chamber prints.
Freebore diameter was changed to 0.224" for a better bullet seal, excess freebore was later found to be favorable to 69gr mag length and 80 gr single fed rounds.
Finally got the upper shipped back to Criterion this morning. They sent me a prepaid UPS label within a day of me sending the last update with the blown primers after switching to an EBCG but I just hadn’t gotten around to getting it in the mail. The CS rep has been super responsive so I’m optimistic about them taking care of this.
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Would like to add a data point to the A5 not wanting to chamber phenomenon. I just picked up a brand new A5 built lower that had noticeably more resistance to charging and grittiness than my other 2. I pulled the spring and buffer and lightly coated Slip 2k grease and then EWL 30 on the spring, buffer and as far inside the tube as I could get. After running it manually a dozen times, it became much easier and smoother to run the charging handle.
I wonder if some of the difficulties people have had are related to this. FWIW.
Hmm. Thats not a bad point. I think I stopped oiling springs about the same time I started shooting A5s a lot, because stainless GI springs. Although, I must point out that this procedure is totally unnecessary with a GI carbine setup.
I’ll try to remember to give that a try.
Would like to add a data point to the A5 not wanting to chamber phenomenon. I just picked up a brand new A5 built lower that had noticeably more resistance to charging and grittiness than my other 2. I pulled the spring and buffer and lightly coated Slip 2k grease and then EWL 30 on the spring, buffer and as far inside the tube as I could get. After running it manually a dozen times, it became much easier and smoother to run the charging handle.
I wonder if some of the difficulties people have had are related to this. FWIW.
I see that you have owned a JP Ground & Polished carbine spring so you know how smooth those are. Have you tried the rifle version in the A5?
I see that you have owned a JP Ground & Polished carbine spring so you know how smooth those are. Have you tried the rifle version is the A5?I haven't, but now that you mention it, I think I'm going to order a pair.
Finally got the upper shipped back to Criterion this morning. They sent me a prepaid UPS label within a day of me sending the last update with the blown primers after switching to an EBCG but I just hadn’t gotten around to getting it in the mail. The CS rep has been super responsive so I’m optimistic about them taking care of this.
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Upper got there on the 12th, finally heard back today. I’d sent two emails just trying to confirm that it got where it needed to go and both went unanswered. A month at Criterion and going from extremely responsive to no response at all was less than ideal. I was starting to wonder if the CS rep had gotten in a car accident or something.
That said, the rep measured both BCGs I sent in and stated that both were too small to headspace properly. This seems odd for two different bolts, one Geissele and one LMT E-bolt, both of which head spaced correctly off of normal gauges. However, he had previously stated that Criterion holds tighter tolerances so it’s not entirely surprising that my head space gauge didn’t match theirs. Either way, he included a headspaced BCM bolt and it should be on the way back to me.
One more email saying that he got the upper but it might take a minute to go through would’ve been awesome but assuming this was the issue and it’s all resolved now, their CS was great IMO. I absolutely can’t complain about getting a headspaced BCM bolt free of charge, especially considering they offer Fulton Armory BCGs on their sight for less than the BCMs and he could’ve given me a bolt from them, or just charged me. His responses were always detailed as well. I’ve definitely had CS experiences where I sent something in and then get an email stating that it’s coming back (SureFire did it today). Having a rep take the time to write more than one sentence and actually inform the end user of the issue is part of what separates good and great CS.
Unfortunately I’ll be gone for work for a lot of this summer and probably won’t get to test it out any time soon. Agin though, assuming this fixed the issue, there’s a good chance Criterion will stay at the top of my list the next time I need a barrel, I’ll just make sure to get a headspaced bolt with it too.
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Upper got there on the 12th, finally heard back today. I’d sent two emails just trying to confirm that it got where it needed to go and both went unanswered. A month at Criterion and going from extremely responsive to no response at all was less than ideal. I was starting to wonder if the CS rep had gotten in a car accident or something.
That said, the rep measured both BCGs I sent in and stated that both were too small to headspace properly. This seems odd for two different bolts, one Geissele and one LMT E-bolt, both of which head spaced correctly off of normal gauges. However, he had previously stated that Criterion holds tighter tolerances so it’s not entirely surprising that my head space gauge didn’t match theirs. Either way, he included a headspaced BCM bolt and it should be on the way back to me.
One more email saying that he got the upper but it might take a minute to go through would’ve been awesome but assuming this was the issue and it’s all resolved now, their CS was great IMO. I absolutely can’t complain about getting a headspaced BCM bolt free of charge, especially considering they offer Fulton Armory BCGs on their sight for less than the BCMs and he could’ve given me a bolt from them, or just charged me. His responses were always detailed as well. I’ve definitely had CS experiences where I sent something in and then get an email stating that it’s coming back (SureFire did it today). Having a rep take the time to write more than one sentence and actually inform the end user of the issue is part of what separates good and great CS.
Unfortunately I’ll be gone for work for a lot of this summer and probably won’t get to test it out any time soon. Agin though, assuming this fixed the issue, there’s a good chance Criterion will stay at the top of my list the next time I need a barrel, I’ll just make sure to get a headspaced bolt with it too.
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I hope that gets it running correctly. I know I've been eyeing another one of their barrels for a LW SPR type.
Sorry to hear of blown primers in your barrel, with the MEN amm ( and Igman )
FWIW, I have fired a decent amount of MEN 5.56 and never had an issue. Do you happen to have the Lot # and about when did you purchase it ?
Mine is from years ago. It was boringly consistent function wise. Accuracy is respectable from the various AR's I have shot it from. Especially considering the FMJ aspect.
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