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Posted: 4/9/2015 12:47:03 PM EDT
[#1]
Sounds a lot like an over pressure issue, most likely due to the ammo.
Measure the length of one or more of the rounds and report back. |
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Posted: 4/9/2015 12:52:39 PM EDT
[#2]
Thanks for your quick reply. 2.25" exactly. I was going to get a CM tape measure, but it's right on the money at 2 and one quarter inches.
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Posted: 4/9/2015 12:58:17 PM EDT
[#3]
5.57cm
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Posted: 4/9/2015 1:45:09 PM EDT
[#4]
You're getting high pressure signs. For whatever reason this ammo is loaded too hot for your firearm.
What other ammo have you tried? Has any of it given you any problems? CBC claims 2750 fps with their 77 grain load. They don't mention what length barrel they used to get that velocity. 2650 fps is pretty much tops from a 20" barrel before going over SAAMI specs. 2700 fps from a 20" is about all you can expect when loaded to 5.56mm NATO pressure. Leaving ammo sit in the sun will drive pressure up considerably. If it's already loaded hot this could be your problem. All new rifles must be cleaned prior to firing them the first time. I would clean it and lube then try some different ammo. M193 just to see what the primers look like. If you get pressure signs with all ammo contact KAC. If you only get it with CBC, contact them. |
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Posted: 4/9/2015 2:09:56 PM EDT
[#5]
Thanks a lot for your input.
I have about 2,000 rounds through the gun. I cleaned it before the first firing, and after every range trip. I have tried other loadings earlier, and I did not have problems. Specifically X-Tac 62gr, and some 55gr stuff (buddy brought it, not sure of brand). I bought the CBC lot because it seemed like a good cartridge at a great price. ($0.57 I think when I picked them up. This certainly has happened religiously when I use the CBC ammo the last three times, so I was thinking it was the ammunition as well. Sun exposure may have happened, but not on my watch. All ammo stored indoors with A/C. I need to try out these DoubleTap 80grs out anyway, so then we'll see who I need to contact. I'll put 100 or so downrange, then clean and inspect. I realize this may seem like a dumb post by a guy with under 10 posts to his name, but here's my thinking on it: My first thought was the ammunition as well. That being said, all the primer smashing threads I found were either guys who were building (or built) their AR themselves, or those who are reloading. I didn't do either. Stock rifle with stock internals, and commercial ammo. I thought I'd get the community's thoughts, I appreciate it. I'll check back in after the DoubleTaps. (I'm also pleased your gut reaction seems to be the cartridges) |
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Posted: 4/9/2015 2:33:01 PM EDT
[#6]
Quote HistoryQuoted:
Thanks a lot for your input. I have about 2,000 rounds through the gun. I cleaned it before the first firing, and after every range trip. I have tried other loadings earlier, and I did not have problems. Specifically X-Tac 62gr, and some 55gr stuff (buddy brought it, not sure of brand). I bought the CBC lot because it seemed like a good cartridge at a great price. ($0.57 I think when I picked them up. This certainly has happened religiously when I use the CBC ammo the last three times, so I was thinking it was the ammunition as well. Sun exposure may have happened, but not on my watch. All ammo stored indoors with A/C. I need to try out these DoubleTap 80grs out anyway, so then we'll see who I need to contact. I'll put 100 or so downrange, then clean and inspect. I realize this may seem like a dumb post by a guy with under 10 posts to his name, but here's my thinking on it: My first thought was the ammunition as well. That being said, all the primer smashing threads I found were either guys who were building (or built) their AR themselves, or those who are reloading. I didn't do either. Stock rifle with stock internals, and commercial ammo. I thought I'd get the community's thoughts, I appreciate it. I'll check back in after the DoubleTaps. (I'm also pleased your gut reaction seems to be the cartridges) I had multiple blown primers on some factory loaded 300BLK. My 1st thought was overpressure but it turned out to be bad brass. They had a whole lot come from their subcontractor that was bad. I sent it back for testing / replacement, It took a while but they replaced it and gave me quite a bit extra for my troubles. The new stuff was fine. It can happen even to one of the big companies. Take some pictures, including the lot number on the box and email them. I'm guessing they will do the same thing, have you send it back at their expence and eventually make good plus give you some extra for your trouble. 
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Posted: 4/9/2015 3:03:20 PM EDT
[#7]
Good man. You were absolutely right. I called Magtech, since they distribute for CBC and I don't speak Portuguese. Guy was awesome who answered the phone and genuinely interested.
I'm heading to the range tonight to make him some specimens, as I foolishly left brass behind the last time. I'm sending him pictures, the lot numbers and some spent casings as well. So far I couldn't be more pleased with how fast and professionally they are handling it. |
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Posted: 4/9/2015 6:46:49 PM EDT
[#8]
It's the KAC... Same issues here with multiple uppers and multiple manufacturers.
Try running some Independence M193 then standard Federal M193 and report back |
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Posted: 4/9/2015 6:54:16 PM EDT
[#9]
Here's an update. I went to the range tonight and got 10 rounds downrange before failure.
I was able to recover 8 casings. (Two went over the firing line...) It pleased me that I got one example of every busted primer I've seen. (Totally gone, punctured, and "hernia") The other picture are the primer pieces (presumably from the punctured examples) found inside my bolt. I'll let you know what Magtech/CBC says. 
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Posted: 4/9/2015 6:55:48 PM EDT
[#10]
Quote HistoryQuoted:
It's the KAC... Same issues here with multiple uppers and multiple manufacturers. Try running some Independence M193 then standard Federal M193 and report back No problem. Probably get to it on Saturday. Strange the KAC would be fine with the other stuff but not this brand. I'll try either of those brands and report back. |
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Posted: 4/9/2015 7:01:35 PM EDT
[#11]
Quote HistoryQuoted:
No problem. Probably get to it on Saturday. Strange the KAC would be fine with the other stuff but not this brand. I'll try either of those brands and report back. Quote HistoryQuoted:
Quoted:
It's the KAC... Same issues here with multiple uppers and multiple manufacturers. Try running some Independence M193 then standard Federal M193 and report back No problem. Probably get to it on Saturday. Strange the KAC would be fine with the other stuff but not this brand. I'll try either of those brands and report back. It's a weird issue with some KAC 5.56 rifles. I'm guessing the standard Federal M193 will function 100% while the Independence will do the same as the CBC. Best of luck to you |
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Posted: 4/9/2015 7:49:22 PM EDT
[#12]
I just purchased an SR15 E3 MOD 2 and have been having the same problems with blown primers. Ferderal XM193, Idependence AR556 (M193) and even two Hornday TAP 556. If it was only one type of bullet it would be easy to just avoid it but Federal XM193 is the most common ammo around where I live.
Has anyone got answers as to what has caused the problems??? |
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Posted: 4/9/2015 8:06:14 PM EDT
[#13]
Check the tip of your firing pin for damage. Also stop shooting this till you get the issue resolved lest you erode your firing pin hole on your bolt.
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Posted: 4/9/2015 8:07:17 PM EDT
[#14]
A guy I know also has an SR-15 so we're going to try his, and a SW MP15.
See if it is the ammunition, or the gun. In addition, I'll be in contact with both KAC and Magtech (CBC). I'll post updates as I get them on this thread. Good to know it's not just me. |
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Posted: 4/9/2015 8:09:45 PM EDT
[#15]
Quote HistoryQuoted:
Check the tip of your firing pin for damage. Also stop shooting this till you get the issue resolved lest you erode your firing pin hole on your bolt. No damage. Direct compare with the spare pin I keep. Even swapped in the new one for the last range session. I agree with you on shelving her. I'm throwing her in the safe until I figure it out from either KAC or Magtech. (CBC) I'll make sure to follow up on this thread. |
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Posted: 4/9/2015 10:37:49 PM EDT
[#16]
Quoted:
I recently made my first post, here regarding blown primer gumming up my firing pin and seizing the bolt. I thought I'd found and fixed it. Not the case, for I have only identified the problem. I recently bought 1,000 rnds of CBC 77gr OTM to use in my KAC SR-15 MOD 2. I cannot go to the range and get more than 20-50 rounds through it before the bolt becomes jammed. Every time, when I get home I find small brass pieces roughly the same diameter as the firing pin inside the bolt in the firing pin hole. Some of the brass has wear on the headstamp, some have holes in the primer, and even a couple look like "primer hernias" if you will. It looks almost like the primer was stretched inside the case by the firing pin, then the powder blew back out the stretched primer. I'm using commercial grade, quality ammunition (or so my research says). Any suggestions as to what the cause of this is? I've even tried using different lots of the same cartridge...with the same results. Would appreciate any feedback the community has, it's frustrating the heck out of me. You should of gone with the IMI 77gr. Razor Core. The stuff is incredibly reliable for the money. |
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Posted: 4/9/2015 10:54:00 PM EDT
[#17]
Read about it, never tried it. Certainly on the menu for the next bulk purchase.
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Posted: 4/10/2015 2:52:28 AM EDT
[#18]
Quote HistoryQuoted:
You should of gone with the IMI 77gr. Razor Core. The stuff is incredibly reliable for the money. I have had good luck (i.e. performance) with IMI 77gr in 10.3 and 14.5" guns. |
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Posted: 4/10/2015 8:17:16 AM EDT
[#19]
Have you checked the chamber and throat dimensions?
I'll bet that the leade is cut short, or the chamber neck is tight... |
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Posted: 4/10/2015 9:39:32 AM EDT
[#20]
Quote HistoryQuoted:
Have you checked the chamber and throat dimensions? I'll bet that the leade is cut short, or the chamber neck is tight... I have not. That being said, the rifle is on the way to KAC as we speak. Lisa over there responded to my request immediately. (As in I emailed at 8:45pm last night, and had a reply by 8:00am the next day) Working with her has been great so far, you mark response time in minutes, not even hours. Very pleased how both companies are treating me. I'm giving samples of spent casings to Magtech, and the rifle + fresh rounds for KAC. Since I'm working both sides of it, I'm confident I will have an answer soon. |
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Posted: 4/10/2015 10:00:06 AM EDT
[#21]
Quote HistoryQuoted:
I have not. That being said, the rifle is on the way to KAC as we speak. Lisa over there responded to my request immediately. (As in I emailed at 8:45pm last night, and had a reply by 8:00am the next day) Working with her has been great so far, you mark response time in minutes, not even hours. Very pleased how both companies are treating me. I'm giving samples of spent casings to Magtech, and the rifle + fresh rounds for KAC. Since I'm working both sides of it, I'm confident I will have an answer soon. Quote HistoryQuoted:
Quoted:
Have you checked the chamber and throat dimensions? I'll bet that the leade is cut short, or the chamber neck is tight... I have not. That being said, the rifle is on the way to KAC as we speak. Lisa over there responded to my request immediately. (As in I emailed at 8:45pm last night, and had a reply by 8:00am the next day) Working with her has been great so far, you mark response time in minutes, not even hours. Very pleased how both companies are treating me. I'm giving samples of spent casings to Magtech, and the rifle + fresh rounds for KAC. Since I'm working both sides of it, I'm confident I will have an answer soon. Let us know how it turns out. As an aside, customer service is what differentiates a good company from a "meh" company. |
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Posted: 4/10/2015 10:00:24 AM EDT
[#22]
Update. Just heard back from Magtech, speaking with a guy named Jeff, who is dialed in.
I sent him pictures, and he's having me ship my remaining cartridges, and spent casings for inspection. He's already said he would replace the lots affected at their shipping expense. Very pleased, especially since we haven't verified yet whether it is the rifle or the ammunition. So, both the rifle and the ammo are going back to their respective companies. Once their experts weigh in, I'll let you know what the problem was. With so many negative internet rants on there, I would like to re-iterate both KAC and Magtech have been phenomenal at responding quickly and standing behind their products. |
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Posted: 4/10/2015 10:06:21 AM EDT
[#23]
As an aside, customer service is what differentiates a good company from a "meh" company.
I will. I agree with you wholeheartedly. It makes a huge difference. |
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Posted: 4/10/2015 10:18:18 AM EDT
[#24]
Quote HistoryQuoted: Update. Just heard back from Magtech, speaking with a guy named Jeff, who is dialed in. I sent him pictures, and he's having me ship my remaining cartridges, and spent casings for inspection. He's already said he would replace the lots affected at their shipping expense. Very pleased, especially since we haven't verified yet whether it is the rifle or the ammunition. So, both the rifle and the ammo are going back to their respective companies. Once their experts weigh in, I'll let you know what the problem was. With so many negative internet rants on there, I would like to re-iterate both KAC and Magtech have been phenomenal at responding quickly and standing behind their products. You more than likely got positive results from those chiming in because you posted outside of GD, and didn't start off your topic with something like, "DD is a shit rifle", or "this ammo trashed my rifle." I'm willing to bet that you have a tight, or OOS chamber that isn't allowing the bolt to extract easly. |
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Posted: 4/10/2015 10:21:58 AM EDT
[#25]
Lisa over at KAC is awesome. I'm very interested to see what they say.
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Posted: 4/10/2015 10:32:29 AM EDT
[#26]
Quote HistoryQuoted:
You more than likely got positive results from those chiming in because you posted outside of GD, and didn't start off your topic with something like, "DD is a shit rifle", or "this ammo trashed my rifle." I'm willing to bet that you have a tight, or OOS chamber that isn't allowing the bolt to extract easly. Quote HistoryQuoted:
Quoted:
Update. Just heard back from Magtech, speaking with a guy named Jeff, who is dialed in. I sent him pictures, and he's having me ship my remaining cartridges, and spent casings for inspection. He's already said he would replace the lots affected at their shipping expense. Very pleased, especially since we haven't verified yet whether it is the rifle or the ammunition. So, both the rifle and the ammo are going back to their respective companies. Once their experts weigh in, I'll let you know what the problem was. With so many negative internet rants on there, I would like to re-iterate both KAC and Magtech have been phenomenal at responding quickly and standing behind their products. You more than likely got positive results from those chiming in because you posted outside of GD, and didn't start off your topic with something like, "DD is a shit rifle", or "this ammo trashed my rifle." I'm willing to bet that you have a tight, or OOS chamber that isn't allowing the bolt to extract easly. As my dad once said: "You can always start by being nice guy, and switch to be an a-hole if need be. You can never be an a-hole and then switch to being a nice guy." The way I look at it? If I'm not smart/experienced enough to identify and fix the problem, to the point where I need to go to a forum for advice...I'm probably not smart/experienced enough to start throwing accusations around of what failed. I'm putting you down for $0.50 on OOS chamber for the pool. |
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Posted: 4/11/2015 5:50:02 AM EDT
[#27]
And the good news is, Fluffy's potentially getting a fix from both vendors.
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Posted: 4/11/2015 10:00:51 AM EDT
[#28]
Quote HistoryQuoted:
And the good news is, Fluffy's potentially getting a fix from both vendors. Forgot to update the board, my fault. After sending off my rifle to Lisa at KAC yesterday, I spoke with Jeff from Magtech again. We're going to wait on shipping back (call it 1500rnds) until we hear from KAC. If KAC says it looks great, ammo swap. If KAC says something's not in spec, I'll try the same ammo with the fix they provide. I read your post, and then thought: "Fluffy?" What, like that Hispanic comedian.....oh right my user name." That's from this: https://www.youtube.com/watch?v=7_0ava_MSSw |
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Posted: 4/16/2015 2:20:07 PM EDT
[#29]
Update: Rifle arrived at KAC and is being checked in/testing begins.
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Posted: 4/16/2015 9:14:32 PM EDT
[#30]
Tag for useful thread.
Good on you OP for posting updates. 
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Posted: 4/23/2015 4:28:21 PM EDT
[#31]
Update: Rifle on it's way back. Here's what KAC said, looks like an issue with both the ammunition and the rifle.
"They did replace the bolt. There is really not an explanation on the heavy wear around the bolt lugs. Here is the function test information and also the ammo that they used: Function test 55gr PMC No issues 55gr XM193 No issues 62gr M855 No issues 77 gr Win match No issues 77gr CBC heavy Primer flow no punches this time or blown primers 22 Apr 2015 Function test Standard colt M-4 same results heavy primer flow with almost punched primers So weapon has new bolt assembly and has been head spaced and checked and function tested" I'm leaning towards ammo since they didn't have an explanation for the bolt wear and also the fact it was acting up on the Colt function test. |
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Posted: 4/23/2015 5:38:07 PM EDT
[#32]
Lean towards chamber,
Military chambers are produced with wider cross wall dimensions than civilian barrels , and this allows for the rifle to run more reliable in full auto sustained adverse conditions. In the civilian chambers, the side wall dimensions are held tighter to promote accuracy instead. So when this import ammo is loaded to 62K PSI, and with slower burning powder for the heaver bullet, the gas blow by on the civilian chambers at fire forming of the brass to the chamber at ignition is decreased, which increases achieved pressure of the round in the barrel instead. Bluntly, if you where to grab a M-16 rifle (colt or FN) our of an armory rack, the ammo would run fine it it. Also will run fine in the G36 rifle, since that is Portuguese current service rifle that that ammo was designed for (also a service rifle with a wider side wall chamber dimensions as well). The down side, the M-16/G36 standards for accuracy is only 3 moa (effective for man side targets out to 600 meters), and you would pissed if this is the best that your rifle could do instead. |
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Posted: 4/23/2015 7:16:03 PM EDT
[#33]
Quote HistoryQuoted:
Lean towards chamber, Military chambers are produced with wider cross wall dimensions than civilian barrels , and this allows for the rifle to run more reliable in full auto sustained adverse conditions. In the civilian chambers, the side wall dimensions are held tighter to promote accuracy instead. So when this import ammo is loaded to 62K PSI, and with slower burning powder for the heaver bullet, the gas blow by on the civilian chambers at fire forming of the brass to the chamber at ignition is decreased, which increases achieved pressure of the round in the barrel instead. Bluntly, if you where to grab a M-16 rifle (colt or FN) our of an armory rack, the ammo would run fine it it. Also will run fine in the G36 rifle, since that is Portuguese current service rifle that that ammo was designed for (also a service rifle with a wider side wall chamber dimensions as well). The down side, the M-16/G36 standards for accuracy is only 3 moa (effective for man side targets out to 600 meters), and you would pissed if this is the best that your rifle could do instead. That all makes perfect sense. What do you make of primer issues on the Colt M4 control firearm? Wouldn't that be Military spec? (Or do you think they used a civilian version on that one as well?) You don't find it curious the CBC had issues on both guns at all? Are you basically saying this particular cartridge might have issues in any civilian direct impingement firearm? |
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Posted: 4/23/2015 11:45:57 PM EDT
[#34]
Quote HistoryQuoted:
Sun exposure may have happened, but not on my watch. All ammo stored indoors with A/C.) While your shooting. An increase from 70 to 120 F can drive the pressure up 7000 psi or more. |
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Posted: 4/24/2015 12:02:38 AM EDT
[#35]
Quote HistoryQuoted:
Lean towards chamber, Military chambers are produced with wider cross wall dimensions than civilian barrels , and this allows for the rifle to run more reliable in full auto sustained adverse conditions. In the civilian chambers, the side wall dimensions are held tighter to promote accuracy instead. So when this import ammo is loaded to 62K PSI, and with slower burning powder for the heaver bullet, the gas blow by on the civilian chambers at fire forming of the brass to the chamber at ignition is decreased, which increases achieved pressure of the round in the barrel instead. Bluntly, if you where to grab a M-16 rifle (colt or FN) our of an armory rack, the ammo would run fine it it. Also will run fine in the G36 rifle, since that is Portuguese current service rifle that that ammo was designed for (also a service rifle with a wider side wall chamber dimensions as well). The down side, the M-16/G36 standards for accuracy is only 3 moa (effective for man side targets out to 600 meters), and you would pissed if this is the best that your rifle could do instead. I would hope Reed Knight is making his rifles with NATO spec chambers. |
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Posted: 4/24/2015 10:08:51 AM EDT
[#36]
Update: Sending remaining cartridges and casings back to Magtech. Not sure if my rifle just doesn't like this specific load or what. After all, KAC did think they needed to replace the bolt, but then again the only problems were with this loading... Maybe a little bit of both on this issue.
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Posted: 4/27/2015 8:35:34 PM EDT
[#37]
Update. Rifle back in my possession. Field stripped it to lube it...wow they sent it back detailed. 300 rounds PMC XTAC, 300 rounds Magtech 62gr FMJ, 100 rounds DoubleTap 80gr OTM. Flawless.
Replacement Magtech 5.56 coming soon. 
Very pleased with both sides. Rifle looks and runs great. Magtech impressed me a lot. Even though they knew KAC replaced the bolt (I kept them in the loop), they told me "We understand you probably lost faith in that lot. I'd love to replace it for you." Bothers me slightly there was no explanation, but the service from KAC was excellent and the problem is fixed. Very happy with both companies. |
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Posted: 4/28/2015 9:57:52 PM EDT
[#38]
Well KAC has had my rifle about 10 Days. The LE sales guy Ray is very nice but I have never had so much trouble with an AR15. I have even owned bushmasters and done home builds. The department I work for has about 20 guys with colts,lwrc, Daniel defense and rock rivers. None of those rifles are blowing primers. I believe it's an over pressure issue but it sure sucks the most expensive rifle can't run xm193 or Hornady TAP ammo without blown primers. As long as they fix it I will be happy but we sure haven't got started on the right foot. I even sent them over 200 rounds of the two brands of problem ammo so they should have the same failures. If the problem exist I will send Federal their ammo back and let them know Knights said its over pressured. Keeping my fingers crossed. I will keep you guys updated.
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