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Posted: 10/29/2012 9:48:30 AM EDT
| I recently acquired a brand new Daniel Defense M4v7 & loaded some rounds to take it out & sight it in. I loaded Hornady 55 grain sp w/ cannelure, on top 25.5 grains of Varget, CCI 400 primers, 2.20" oal, Remington commercial brass trimmed to 1.750". I'm a little concerned because out of the 150 rounds that I shot, 2 of the primers were pierced. The rest of the brass looked good & had no pressure signs, no cratering, etc. The guy I was with said that it was no big deal, & probably just a thin primer cup or the primer wasn't seated deep enough. Upon further inspection the primers appeared to be seated deep enough. I wanted to get opinions on why this happened so that I don't risk messing up my brand new rifle. |
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I recently acquired a brand new Daniel Defense M4v7 & loaded some rounds to take it out & sight it in. I loaded Hornady 55 grain sp w/ cannelure, on top 25.5 grains of Varget, CCI 400 primers, 2.20" oal, Remington commercial brass trimmed to 1.750". I'm a little concerned because out of the 150 rounds that I shot, 2 of the primers were pierced. The rest of the brass looked good & had no pressure signs, no cratering, etc. The guy I was with said that it was no big deal, & probably just a thin primer cup or the primer wasn't seated deep enough. Upon further inspection the primers appeared to be seated deep enough. I wanted to get opinions on why this happened so that I don't risk messing up my brand new rifle. There are a lot of reasons why it could happen. I had a box of heavies I loaded up and got 4-7 pierced primers and just chalked it up to possibly too much pressure. It's pretty much tough to micro-manage after the fact when a small sample size fails out of many. Maybe neck tension was too high on the pair, maybe you had too much crimp, maybe your charge was a bit excessive, maybe the powder was a bit slow and as your buddy mentioned, maybe it was just those primer cups? Varget and the 55s are something I don't use together, but if that combo works for you, more power to you. Chris |
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I recently acquired a brand new Daniel Defense M4v7 & loaded some rounds to take it out & sight it in. I loaded Hornady 55 grain sp w/ cannelure, on top 25.5 grains of Varget, CCI 400 primers, 2.20" oal, Remington commercial brass trimmed to 1.750". I'm a little concerned because out of the 150 rounds that I shot, 2 of the primers were pierced. The rest of the brass looked good & had no pressure signs, no cratering, etc. The guy I was with said that it was no big deal, & probably just a thin primer cup or the primer wasn't seated deep enough. Upon further inspection the primers appeared to be seated deep enough. I wanted to get opinions on why this happened so that I don't risk messing up my brand new rifle. There are a lot of reasons why it could happen. I had a box of heavies I loaded up and got 4-7 pierced primers and just chalked it up to possibly too much pressure. It's pretty much tough to micro-manage after the fact when a small sample size fails out of many. Maybe neck tension was too high on the pair, maybe you had too much crimp, maybe your charge was a bit excessive, maybe the powder was a bit slow and as your buddy mentioned, maybe it was just those primer cups? Varget and the 55s are something I don't use together, but if that combo works for you, more power to you. Chris My buddy said pretty much the same thing, with only having 2 pierced primers out of 150. I guess I'm just being over cautious, but better safe than sorry. I use Varget to try to simplify things, since I use the same powder for 308. Just makes it easier keeping one powder on hand for rifle cartridges. It yielded about 1"-1.5" groups at 100 yards. I was fairly pleased with the results. |
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Two biggest causes, excess or long rifle headspace or short cartridge headspace, both will cause excess head clearance meaning too much "air space" between the rear of the case and the bolt face.
The firing pin drives the cartridge forward to where the shoulder of the case is stopped by the shoulder of the chamber. The cartridge goes "bang" and the chamber pressure pushes the primer back and out of the primer pocket and back over the protruding firing pin. This action turns the firing pin into a cookie cutter and the firing pin punches the hole in the firing pin. This just one of the reasons military ammunition has crimped primers to prevent this on long headspaced military rifles. Below watch the primer being forced to the rear by the chamber pressure and then be reseated as the cartridge case is forced to the rear. In actuality the primer is taking two separate "hits" and this can punch the center out of the primer if you have excess head clearance or "air space" between the rear of the case and the bolt face. 
Pierced primers can also be caused by too much firing pin protrusion or by the firing tip not being shaped correctly. 
Below is another example of a British .303 with headspace and head clearance explained, again watch the primer move to the rear when fired. (head clearance is the "air space" between the rear of the case and the bolt face) 
Over resizing your cases can create "excess air space" between the rear of your cases and the bolt face, check your sized cases! |
| Use a thicker primer cup .025" http://www.jamescalhoon.com/primers_and_pressure.php |
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Do you notice anything about the indents of the ones that did not pierce?
Our new build (all new parts) was pierced primers but the indent was not smooth and rounded. A close look at the firing pin tip (a lighted magnifying glass) revealed a small burr left over buy the turning operation of the tip. I chucked up the pin in my cordless drill and polished it with a FINE oil stone. This corrected the problem. I use a Rem 6 1/2 primer for light loads. This is a this cup primer and should not be used for "regular" .223 loads. After "the fix" it does not even pierce these. |
| I've read that an irregular firing pin or short/excessive headspace of the rifle could cause a pierced primer, I just would think that it would happen more often than 2 out of 150. Am I wrong to think that? Also, wouldn't all of the brass be showing signs of excess pressure (ie cratered primers) Thanks for the suggestions! |
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After two pierced primers you had better check the end of the firing pin for a pit and correct it. Every time a primer pierces a jet of hot gas erodes the pin, and the piercings plus wear accelerates until the primer pierces on every shot; the firing pin was ruined beyond saving long before that.
You are using a thin primer with a charge weight that is warm enough, so pierced primers shouldn't be a surprise. |
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After two pierced primers you had better check the end of the firing pin for a pit and correct it. Every time a primer pierces a jet of hot gas erodes the pin, and the piercings plus wear accelerates until the primer pierces on every shot; the firing pin was ruined beyond saving long before that. You are using a thin primer with a charge weight that is warm enough, so pierced primers shouldn't be a surprise. I took the pin out, & as far as I can tell it looks normal. The tip of the pin is tiny. I didn't see a pit or anything glaring that stood out. Hopefully, all is well. |
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After two pierced primers you had better check the end of the firing pin for a pit and correct it. Every time a primer pierces a jet of hot gas erodes the pin, and the piercings plus wear accelerates until the primer pierces on every shot; the firing pin was ruined beyond saving long before that. You are using a thin primer with a charge weight that is warm enough, so pierced primers shouldn't be a surprise. I took the pin out, & as far as I can tell it looks normal. The tip of the pin is tiny. I didn't see a pit or anything glaring that stood out. Hopefully, all is well. Get a jeweler's loop––a 8x-10x and look. My pin has some errosion and it's pretty neat to see it after the fact. I took some of my Lansky stones and licked it a few times, but it did happened in my case...not to the point that I get pierced primers, but that hot gas does errode the aluminum firing pin's tip. You should always carry a couple of spare firing pins, anyhow, since they're cheap. Chris |
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You have a thin primer issue signaled by that tit in the center of the firing pin indentation. So is it a bad batch of CCI 400's or is CCI known for thin primers? I've had no issues with their large rifle or small pistol primers with warm to moderate loads. My thinking led me to believe that the tit in the center of the firing pin indention was due to the fact the firing pin had a pit on it and it was transferred to the primer. |
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Quoted: Quoted: You have a thin primer issue signaled by that tit in the center of the firing pin indentation. So is it a bad batch of CCI 400's or is CCI known for thin primers? I've had no issues with their large rifle or small pistol primers with warm to moderate loads. My thinking led me to believe that the tit in the center of the firing pin indention was due to the fact the firing pin had a pit on it and it was transferred to the primer. You are using the wrong CCI SR primer. Go to a CCI 41. |
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You have a thin primer issue signaled by that tit in the center of the firing pin indentation. So is it a bad batch of CCI 400's or is CCI known for thin primers? I've had no issues with their large rifle or small pistol primers with warm to moderate loads. My thinking led me to believe that the tit in the center of the firing pin indention was due to the fact the firing pin had a pit on it and it was transferred to the primer. You are using the wrong CCI SR primer. Go to a CCI 41. Moving forward, I'll be switching primers. I'm not sure if I've seen CCI 41 locally. Would the 450 be suitable as well?. What do you think about the firing pin dryflash3? |
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Double check the firing pin to see if it has an unusually small radius on the end, if it's not eroded. However, I have seen exactly the same symptom with good firing pins when I was shooting the old WSR primers. When that tit shows up, you'll see more piercing with the next increment of gunpowder.
Remington 7 1/2 primers will work, but they are just a little more expensive. Do not buy 6 1/2's, you'll really have a problem then. In fact, the CCI 400 is the same thickness as the Rem 6 1/2, but we don't know if the cups of the CCI primer are annealed or left hard after forming, so they might be a little stouter anyway. |
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Double check the firing pin to see if it has an unusually small radius on the end, if it's not eroded. However, I have seen exactly the same symptom with good firing pins when I was shooting the old WSR primers. When that tit shows up, you'll see more piercing with the next increment of gunpowder. Remington 7 1/2 primers will work, but they are just a little more expensive. Do not buy 6 1/2's, you'll really have a problem then. In fact, the CCI 400 is the same thickness as the Rem 6 1/2, but we don't know if the cups of the CCI primer are annealed or left hard after forming, so they might be a little stouter anyway. Ok so Remington 7 1/2's or CCI 41's are GTG. What do you think about the 450's (I know I've seen these locally)? I'm not sure about the firing pin. I've looked to the best of my ability and don't see anything. I would post a picture of the firing pin but I don't think that I can get my camera to focus on such a small point. I might just play it safe and get a new pin from BCM. I'm just not looking forward to the task ahead. I've go to pull and de-prime 850 rounds that I can't fire safely. FML!  On side note I chose this load, powder, primers, bullets, b/c my FIL shoots the same load out of his Black Rain Ordnance AR-15 with no issues.
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Quoted: Quoted: Quoted: Quoted: You have a thin primer issue signaled by that tit in the center of the firing pin indentation. So is it a bad batch of CCI 400's or is CCI known for thin primers? I've had no issues with their large rifle or small pistol primers with warm to moderate loads. My thinking led me to believe that the tit in the center of the firing pin indention was due to the fact the firing pin had a pit on it and it was transferred to the primer. You are using the wrong CCI SR primer. Go to a CCI 41. Moving forward, I'll be switching primers. I'm not sure if I've seen CCI 41 locally. Would the 450 be suitable as well?. What do you think about the firing pin dryflash3? I have never used CCI 450's, but hear they have thicker cups than CCI 400's. Get a box and try them. |
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JB_DanielD
New thicker primers will not fix a headspace problem or cartridge case that are over resized and have had the shoulder of the case bumped back too far. 1. Are your primers flush with the base of the case or are they protruding. Your photos of your primers indicate low pressure and they might be protruding. 2. If the tip of your firing pin is not eroded from hot high pressure gas leakage then you have excess head clearance or air space between the bolt face and the rear of the case. What you might be seeing is the thinnest compressed section of the firing pin hit in the primer is just bulging outward under pressure. 3. In a normal headspaced rifle, primer thickness in not an issue, thicker primers are used on rifles with floating firing pins to prevent the rifle from discharging on bolt closing. Meaning inertia causing enough energy to fire the primer, if you can release the bolt repeatedly and not have an accidental discharge primer thickness is not an issue. 4. If you do not have cartridge gauges to set up your reloading dies then get some type of gauge to help narrow down your problem. If factory loaded ammunition is not causing the same problem then your reloads are to blame. Below is from the Sierra reloading manual "READ IT".
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JB_DanielD New thicker primers will not fix a headspace problem or cartridge case that are over resized and have had the shoulder of the case bumped back too far. 1. Are your primers flush with the base of the case or are they protruding. Your photos of your primers indicate low pressure and they might be protruding. 2. If the tip of your firing pin is not eroded from hot high pressure gas leakage then you have excess head clearance or air space between the bolt face and the rear of the case. What you might be seeing is the thinnest compressed section of the firing pin hit in the primer is just bulging outward under pressure. 3. In a normal headspaced rifle, primer thickness in not an issue, thicker primers are used on rifles with floating firing pins to prevent the rifle from discharging on bolt closing. Meaning inertia causing enough energy to fire the primer, if you can release the bolt repeatedly and not have an accidental discharge primer thickness is not an issue. 4. If you do not have cartridge gauges to set up your reloading dies then get some type of gauge to help narrow down your problem. If factory loaded ammunition is not causing the same problem then your reloads are to blame. Below is from the Sierra reloading manual "READ IT". http://i122.photobucket.com/albums/o254/bigedp51/primers-a.jpg I sent an email to the manufacturer inquiring about my firing pin. They want me to ship the entire upper back so that they can check it out. All of the primers were flush & I used a cartridge guage to check all of the rounds that I loaded. They all checked out ok. |
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JB_DanielD New thicker primers will not fix a headspace problem or cartridge case that are over resized and have had the shoulder of the case bumped back too far. 1. Are your primers flush with the base of the case or are they protruding. Your photos of your primers indicate low pressure and they might be protruding. 2. If the tip of your firing pin is not eroded from hot high pressure gas leakage then you have excess head clearance or air space between the bolt face and the rear of the case. What you might be seeing is the thinnest compressed section of the firing pin hit in the primer is just bulging outward under pressure. 3. In a normal headspaced rifle, primer thickness in not an issue, thicker primers are used on rifles with floating firing pins to prevent the rifle from discharging on bolt closing. Meaning inertia causing enough energy to fire the primer, if you can release the bolt repeatedly and not have an accidental discharge primer thickness is not an issue. 4. If you do not have cartridge gauges to set up your reloading dies then get some type of gauge to help narrow down your problem. If factory loaded ammunition is not causing the same problem then your reloads are to blame. Below is from the Sierra reloading manual "READ IT". http://i122.photobucket.com/albums/o254/bigedp51/primers-a.jpg I sent an email to the manufacturer inquiring about my firing pin. They want me to ship the entire upper back so that they can check it out. All of the primers were flush & I used a cartridge guage to check all of the rounds that I loaded. They all checked out ok. IMO, just buy a firing pin, or three. They're like $8 a piece. How much are you going to spend shipping the thing back and insuring it? Time at the post office? Chris |
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JB_DanielD New thicker primers will not fix a headspace problem or cartridge case that are over resized and have had the shoulder of the case bumped back too far. 1. Are your primers flush with the base of the case or are they protruding. Your photos of your primers indicate low pressure and they might be protruding. 2. If the tip of your firing pin is not eroded from hot high pressure gas leakage then you have excess head clearance or air space between the bolt face and the rear of the case. What you might be seeing is the thinnest compressed section of the firing pin hit in the primer is just bulging outward under pressure. 3. In a normal headspaced rifle, primer thickness in not an issue, thicker primers are used on rifles with floating firing pins to prevent the rifle from discharging on bolt closing. Meaning inertia causing enough energy to fire the primer, if you can release the bolt repeatedly and not have an accidental discharge primer thickness is not an issue. 4. If you do not have cartridge gauges to set up your reloading dies then get some type of gauge to help narrow down your problem. If factory loaded ammunition is not causing the same problem then your reloads are to blame. Below is from the Sierra reloading manual "READ IT". http://i122.photobucket.com/albums/o254/bigedp51/primers-a.jpg I sent an email to the manufacturer inquiring about my firing pin. They want me to ship the entire upper back so that they can check it out. All of the primers were flush & I used a cartridge guage to check all of the rounds that I loaded. They all checked out ok. IMO, just buy a firing pin, or three. They're like $8 a piece. How much are you going to spend shipping the thing oback and insuring it? Time at the post office? Chris That's what I was planning on doing originally, but I was trying to see if I could get it taken care of by the manufacturer. The customer service rep believes that the issue could be in the bcg, but wants the entire upper back to be sure if there is any issue it will be resolved. Might as well make sure the headspace & everything is GTG. I just would rather be safe than sorry. |
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