Broken Bolt Carrier survey - XDTalk Forums - Your HS2000/SA-XD Information Source!

John A. · 03-04-2008, 02:08 PM

With all the talk about which bolt carrier is the best and the extra step in magnetic particle testing and all the other talk about broken bolts and carriers, I'm wanting to start a running thread to find out just how often it happens. And of course if it happens more with certain brands over another.

If your bolt carrier has broken, let us know and please give an honest estimate of how many rounds were fired and what brand of carrier it was, and if there were other circumstances that may've caused it..ie, bad reload, etc.

Pictures obviously get extra credit.

Slightly off topic, but going on record, I own 3 bolts of various manufacture. 1 LMT with about 1500 through it, and 1 unknown that has about 800 through it and is my newest but is identical to the old Colt SP1 cut, and 1 Olympic Arms (which is my oldest and has around ~15K through it).

Zero breakages.

Please keep in mind, I'm looking for first hand problems. Not something you read and I'm not looking for offsite links. I want to know if it's happened to you.

Let the study begin. I'm looking forward to finding out if all this Magnetic Particle stuff is marketing stratagy or a valid concern. Thanks for participating in the survey. Though I expect this is going to be a quiet topic.

petey1 · 03-04-2008, 02:30 PM

Do you mean just the bolt itself breaking? I've heard of bolts breaking, but never carriers.

John A. · 03-04-2008, 02:36 PM

Bolts or carriers. Even sheared lugs is alright.

Basically if you've had a breakage anywhere on the assembly, I wanna know the details about it.

younggun22 · 03-04-2008, 03:20 PM

i have:

1 sendra -8k no breaks
1 bushmaster - 6k no breaks but a loose gas key ( not properly staked)
2 LMT - 2k each - no breaks

**EricCartmann** · 03-04-2008, 03:54 PM

No problems with any of mine.. but then again all my rifles are fairly new. Heaviest use one only has 4k rounds through it.

**Ed Ely** · 03-04-2008, 05:14 PM

This thread deserves a sticky in order to
gather information which should/would/can
help all we AR affectionatos.

When it runs a course, a couple of months
or so, I will then put it back into the regular
thread flow.

For the record, I have not had an issue...
yet.

Ed

John A. · 03-04-2008, 05:33 PM

Thank you Ed.

**Badshot** · 03-07-2008, 01:46 PM

No issue with BCG's across a total of 8 AR's in 14 years.. can't count the total number of rounds that comes out to, but it's in excess of 100K easily.

WTA_Delta · 03-07-2008, 02:24 PM

Although this is off topic, the military released their test data some time ago, and I am sure many AR "experts" have read this already, but perhaps this will help those that have not:

http://www.dtic.mil/ndia/2006smallar...h=%22sopmod%22

You'll need Abode Acrobat Reader:
Adobe - Adobe Reader Download - All versions

The power point presentation has some good information on the results from testing, bolt wear is more frequent with the M4 than M16 due to higher pressures due to the shortening of the gas tube. The stress point is obvious in the bolt, where the cam pin is inserted, and that is were the cracks tend to propogate.

If I remember correctly they even ran some FEM (Finite-Element) Package, which is a CAD (Computer-Assistant Design) like program that allows the user to input load conditions from point forces, shear forces, pressure, and even radiation (heat). And compared FEM results with test data, and found similar conclusion.

**EricCartmann** · 03-07-2008, 03:01 PM

Quote:

Originally Posted by WTA_Delta

Although this is off topic, the military released their test data some time ago, and I am sure many AR "experts" have read this already, but perhaps this will help those that have not:

http://www.dtic.mil/ndia/2006smallar...h=%22sopmod%22

The power point presentation has some good information on the results from testing, bolt wear is more frequent with the M4 than M16 due to higher pressures due to the shortening of the gas tube. The stress point is obvious in the bolt, where the cam pin is inserted, and that is were the cracks tend to propogate.

If I remember correctly they even ran some FEM (Finite-Element) Package, which is a CAD (Computer-Assistant Design) like program that allows the user to input load conditions from point forces, shear forces, pressure, and even radiation (heat). And compared FEM results with test data, and found similar conclusion.

Thanks for the PDF doc. That doc said the breaking point of an M4 bolt was about 10k rounds for a mildly use M4 with short gas system (mild here meaning semi auto firing mostly). I never knew where people got this info from but I heard a lot of reputable people say it so I just assumed it to be true. One guy told me it is about the end life for a Bushmaster bolt, but turns out is true even for Colts. Moral of the story? Keep a spare bolt.

03-04-2008, 02:08 PM	#1
John A. XDTalk 100 Member Join Date: Jun 2006 Location: KY Posts: 442	Broken Bolt Carrier With all the talk about which bolt carrier is the best and the extra step in magnetic particle testing and all the other talk about broken bolts and carriers, I'm wanting to start a running thread to find out just how often it happens. And of course if it happens more with certain brands over another. If your bolt carrier has broken, let us know and please give an honest estimate of how many rounds were fired and what brand of carrier it was, and if there were other circumstances that may've caused it..ie, bad reload, etc. Pictures obviously get extra credit. Slightly off topic, but going on record, I own 3 bolts of various manufacture. 1 LMT with about 1500 through it, and 1 unknown that has about 800 through it and is my newest but is identical to the old Colt SP1 cut, and 1 Olympic Arms (which is my oldest and has around ~15K through it). Zero breakages. Please keep in mind, I'm looking for first hand problems. Not something you read and I'm not looking for offsite links. I want to know if it's happened to you. Let the study begin. I'm looking forward to finding out if all this Magnetic Particle stuff is marketing stratagy or a valid concern. Thanks for participating in the survey. Though I expect this is going to be a quiet topic. __________________ "The 2nd Amendment wasn't adopted into the Constitution because the authors liked guns or the destruction they could cause, but to give ordinary citizens the ability to protect themselves and their family and to take up arms against anyone in a governmental position who tried to deny those fundamental and God given rights." Ecclesiastes 3: 1-8 Last edited by John A. : 03-04-2008 at 02:27 PM.

03-04-2008, 02:30 PM	#2
petey1 XDTalk 500 Member Join Date: Oct 2006 Location: Upstate NY Posts: 662	Do you mean just the bolt itself breaking? I've heard of bolts breaking, but never carriers. __________________ "No free man shall EVER be barred the use of arms." -Thomas Jefferson springerprecision.com bcsportsmen.org gunfacts.info

03-04-2008, 02:36 PM	#3
John A. XDTalk 100 Member Join Date: Jun 2006 Location: KY Posts: 442	Bolts or carriers. Even sheared lugs is alright. Basically if you've had a breakage anywhere on the assembly, I wanna know the details about it. __________________ "The 2nd Amendment wasn't adopted into the Constitution because the authors liked guns or the destruction they could cause, but to give ordinary citizens the ability to protect themselves and their family and to take up arms against anyone in a governmental position who tried to deny those fundamental and God given rights." Ecclesiastes 3: 1-8

03-04-2008, 03:54 PM	#5
EricCartmann XDTalk 1K Member Join Date: Dec 2006 Posts: 1,153	No problems with any of mine.. but then again all my rifles are fairly new. Heaviest use one only has 4k rounds through it. Last edited by EricCartmann : 03-04-2008 at 04:02 PM.

03-04-2008, 05:14 PM	#6
Ed Ely XDTalk 5K Member Join Date: Mar 2001 Location: 37.65N -84.76W (Elev. 932 ft) Posts: 7,517 Blog Entries: 1	Sticky for the Time Being.... This thread deserves a sticky in order to gather information which should/would/can help all we AR affectionatos. When it runs a course, a couple of months or so, I will then put it back into the regular thread flow. For the record, I have not had an issue... yet. Ed

03-04-2008, 03:20 PM	#4
younggun22 XDTalk 100 Member Join Date: May 2006 Posts: 138	i have: 1 sendra -8k no breaks 1 bushmaster - 6k no breaks but a loose gas key ( not properly staked) 2 LMT - 2k each - no breaks

03-04-2008, 05:33 PM	#7
John A. XDTalk 100 Member Join Date: Jun 2006 Location: KY Posts: 442	Thank you Ed. __________________ "The 2nd Amendment wasn't adopted into the Constitution because the authors liked guns or the destruction they could cause, but to give ordinary citizens the ability to protect themselves and their family and to take up arms against anyone in a governmental position who tried to deny those fundamental and God given rights." Ecclesiastes 3: 1-8

03-07-2008, 01:46 PM	#8
Badshot XDTalk 1K Member Join Date: Dec 2006 Location: Colorado Posts: 1,431	No issue with BCG's across a total of 8 AR's in 14 years.. can't count the total number of rounds that comes out to, but it's in excess of 100K easily. __________________ --------------------- Stupidity should should be painful! On AR15's: Learn to use your Iron Sights before you go adding all that extra crap on your gun!

03-07-2008, 02:24 PM	#9
WTA_Delta XDTalk Member Join Date: Jul 2007 Location: KS Posts: 48	Although this is off topic, the military released their test data some time ago, and I am sure many AR "experts" have read this already, but perhaps this will help those that have not: http://www.dtic.mil/ndia/2006smallar...h=%22sopmod%22 You'll need Abode Acrobat Reader: Adobe - Adobe Reader Download - All versions The power point presentation has some good information on the results from testing, bolt wear is more frequent with the M4 than M16 due to higher pressures due to the shortening of the gas tube. The stress point is obvious in the bolt, where the cam pin is inserted, and that is were the cracks tend to propogate. If I remember correctly they even ran some FEM (Finite-Element) Package, which is a CAD (Computer-Assistant Design) like program that allows the user to input load conditions from point forces, shear forces, pressure, and even radiation (heat). And compared FEM results with test data, and found similar conclusion.

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