This is not going to be a Colt bashing thread. This is in hopes of an honest answer from someone seeking the truth.

In light of a couple other threads I was hoping to get some real information in regards to the magna particle testing Colt performs, specifically. This info may not be obtainable, but hopefully it is.

1. How many defective barrels, bolts, etc (say per 100) are thrown out due to flaws found in magna particle testing.

The reason for this question is quite simple really. It is, I gather, an expensive thing to do, test EVERYTHING. So, if that is the case, hopefully they are doing it because otherwise they would be letting MANY defective products through that shouldn't be allowed out of the factory.

I would assume that conducting this test would mean that there is little room for error in the manufacturing process. Esspecially since it's brought up so much by the Colt crowd.

2. Is there a way to manufacture these things that need Magna Particle testing in a way that would ensure you'd be making less "flawed" products?

3. Does anyone know what the MP testing process includes? Maybe spelled out in lamens terms?

4. Any idea how many barrels Bushmaster MP tests per 100 or whatever?

5. Do any other manufacturers conduct magna particle testing on their parts, whether they do it on every single one, or on test samples out of every batch?

Are the answers to these questions unavailable?

Quoted: 3)  The Colt proof marks of "MP" - do NOT specifically mean "Magnetic Particle Inspected". "MP" is Colt's proof mark for a process done to both bolts and barrels, to include an HPT (High Pressure Test).   Using a M197 Proof Load cartridge, a round is fired with every barrel and bolt.  The proof load is approx 72K PSI (USGI ammo runs approx 50-55K).  After the HPT, the barrel and bolts go through a MPI (Magnetic Particle Inspection) , to check for surface cracks and defects that could not be seen by the human eye.  The idea is that the two most critical parts of the rifle system are put under an additional level of stress.  If both barrels and bolts pass HPT / MPI, then it is an indication of the integrity and the quality. I have said this before but (relating to bolts and barrels) to MPI without HPT is almost worthless, and to HPT without then doing the MPI is probably dangerous. Colt's "MP" = HPT + MPI, in that order. MPI is a Non Destructive Test (NDT) that electrically magnetizes the part to be inspected.  The part is then put under a "black type light" and run through a solution that suspends tiny florescent metal particles (usually water based).  Any microscopic surface cracks attract these particles in the area of the crack.  These accumulated particles show up under the lighting as a florescent line.  I have sat in on some MPIs, and when looked at under normal lighting the crack can be completely invisible-- even if you know where to look. MPI when done properly, is done in two directions that run perpendicular from each other.  As it related to a linear object like a barrel, the barrel is magnetize at both muzzle and chamber then inspected and then magnetized circularly to find cracks that could exist in the other direction. It is normal part of some QA procedures for certain sample lots of certain parts to go through a MPI to better assess the quality of a batch of parts.

BTW the when you get those similarly proofed STAG components in, please be sure to let us know.

It would be interesting to know what percent of the barrels are tested by BM.

It would also be very interesting to know the answer to the original question - What failure percentage does Colt experience?

If the answer is close to zero, then the added value of buying a Colt is questionable. It's easy to use a process, that no one else does, to differentiate your product. The real question is, what value does that process add? What is it really worth?

You see, even if a part "fails" after the high-pressure test load, that does not necessarily mean it would have ever really failed in the field. There is no real-world exact corelation there. Probability? Maybe to some degree. Certainty? Not at all!

OTOH, if the testing produces a fairly high "failure rate" (say, 2% or more) that could make a huge difference. That difference might be worth the extra $$$.

Quoted: It would also be very interesting to know the answer to the original question - What failure percentage does Colt experience? If the answer is close to zero, then the added value of buying a Colt is questionable. It's easy to use a process, that no one else does, to differentiate your product. The real question is, what value does that process add? What is it really worth? You see, even if a part "fails" after the high-pressure test load, that does not necessarily mean it would have ever really failed in the field. There is no real-world exact corelation there. Probability? Maybe to some degree. Certainty? Not at all! OTOH, if the testing produces a fairly high "failure rate" (say, 2% or more) that could make a huge difference. That difference might be worth the extra $$$.

There is the process and there is the end result. Some people are far too consumed with the process

And no one knows the rate of failure of Colt, so it's technically impossible to know the effectiveness of the process. For the record though, it was Colt products that earned the M16 the reputation of being unreliable. Proofing didnt prevent that now did it

Quoted: For the record though, it was Colt products that earned the M16 the reputation of being unreliable. Proofing didnt prevent that now did it

If you knew anything about the history of the development of the M16 and the factors that caused the early variants to be unreliable, like the use of stick powder and non-chromed bores in a humid environment, you would see the ignorance of the statement you just made. Do yourself a favor, go buy a copy of The Black Rifle and read it from cover to cover before you post any more drivel like this.

Quoted: The Black Rifle and read it from cover to cover before you post any more drivel like this.

Thats not going to help.

It has many errors throughout the entire book. It certianly should not be considered a reference guide, more like a coffee table book.

Non-destructive inspection is insurance against bad parts that are considered mission- or safety-critical.  These inspections are often required by the customer (e.g., US Gov) as part of acceptance criteria based upon criticality.  Cost is always weighed against risk.

If you are a frugal hobbyist that only shoots pop cans and paper on the one-way range, buy a "Mil-spec" Bushmaster and take your chances.  A cracked bolt will probably not ruin your day.

If you are purchasing hardware to protect yourself or others and anticipate that you may be dependent upon your hardware to perform reliably on the two-way range, then the minimal added cost of HPT+MPI is cheap insurance.  From this perspective, the bolt/barrel are certainly mission-critical and probably safety-critical (i.e., a failure means you are out of the fight and may even get you killed).

Consider this:  The next time you fly on an aircraft, would you prefer that the airframe manufacturer or tubing supplier NOT have done non-destructive testing on ALL of the high-pressure hydraulic tubes that operate the landing gear, flight-control surfaces, etc. just so you could save a buck on your ticket?

Suppliers do not like to do NDT, because it will find bad parts that must be rejected (scrapped or pawned off on another customer).  Those with excellent quality control will have a high yield (few bad parts); those with poor quality control will have lower yields (more bad parts).  End customers with hard-use requirements cannot stand failures of critical parts in service, so they will pay for the added inspection as insurance.

I think it's a simple answer:

The Colt QC rejects are sold to Civilians.

Quoted: I think it's a simple answer: The Colt QC rejects are sold to Civilians.

Oh yeah,  we're always hearing about how problematic colt Match Targets are!

Quoted: Quoted: For the record though, it was Colt products that earned the M16 the reputation of being unreliable. Proofing didnt prevent that now did it If you knew anything about the history of the development of the M16 and the factors that caused the early variants to be unreliable, like the use of stick powder and non-chromed bores in a humid environment, you would see the ignorance of the statement you just made. Do yourself a favor, go buy a copy of The Black Rifle and read it from cover to cover before you post any more drivel like this.

Oh so I should read a gun mag for information. Does that include how RRA dusted the competition in the DEA trials while all the other makers, including colt, came up short, MP testing and all?

Quoted: Quoted: The Black Rifle and read it from cover to cover before you post any more drivel like this. Thats not going to help. It has many errors throughout the entire book. It certianly should not be considered a reference guide, more like a coffee table book.

I think you're thinking of Black Rifle II - the original is considered THE reference work for the history of ARs - or do you have specific section in mind in the TBR?

Quoted: Quoted: The Black Rifle and read it from cover to cover before you post any more drivel like this. Thats not going to help. It has many errors throughout the entire book. It certianly should not be considered a reference guide, more like a coffee table book.

Ezell was a complete hack.  How did he ever land that curator job at the Smithsonian is beyond me.  Or how about that gig at NASA?  Now that Duncon Long, he is THE MAN!

Quoted: For the record though, it was Colt products that earned the M16 the reputation of being unreliable. Proofing didnt prevent that now did it

I thought that was Mattel?  Are you sure about that, guess I will have to look it up in my Duncon Long book.

I hate to get off the topic but if I was in a fire fight I would want all the MP I could get.  

Quoted: I hate to get off the topic but if I was in a fire fight I would want all the MP I could get.

If I was in a fire fight, I'd want all the ammo I could get

Quoted: Quoted: Quoted: The Black Rifle and read it from cover to cover before you post any more drivel like this. Thats not going to help. It has many errors throughout the entire book. It certianly should not be considered a reference guide, more like a coffee table book. Ezell was a complete hack.  How did he ever land that curator job at the Smithsonian is beyond me.  Or how about that gig at NASA?  Now that Duncon Long, he is THE MAN!

Quoted: Quoted: The Black Rifle and read it from cover to cover before you post any more drivel like this. Thats not going to help. It has many errors throughout the entire book. It certianly should not be considered a reference guide, more like a coffee table book.

Even if you think so, this information is freely available from many historical sources.

Quoted: Quoted: Quoted: 3)  The Colt proof marks of "MP" - do NOT specifically mean "Magnetic Particle Inspected". "MP" is Colt's proof mark for a process done to both bolts and barrels, to include an HPT (High Pressure Test).   Using a M197 Proof Load cartridge, a round is fired with every barrel and bolt.  The proof load is approx 72K PSI (USGI ammo runs approx 50-55K).  After the HPT, the barrel and bolts go through a MPI (Magnetic Particle Inspection) , to check for surface cracks and defects that could not be seen by the human eye.  The idea is that the two most critical parts of the rifle system are put under an additional level of stress.  If both barrels and bolts pass HPT / MPI, then it is an indication of the integrity and the quality. I have said this before but (relating to bolts and barrels) to MPI without HPT is almost worthless, and to HPT without then doing the MPI is probably dangerous. Colt's "MP" = HPT + MPI, in that order. MPI is a Non Destructive Test (NDT) that electrically magnetizes the part to be inspected.  The part is then put under a "black type light" and run through a solution that suspends tiny florescent metal particles (usually water based).  Any microscopic surface cracks attract these particles in the area of the crack.  These accumulated particles show up under the lighting as a florescent line.  I have sat in on some MPIs, and when looked at under normal lighting the crack can be completely invisible-- even if you know where to look. MPI when done properly, is done in two directions that run perpendicular from each other.  As it related to a linear object like a barrel, the barrel is magnetize at both muzzle and chamber then inspected and then magnetized circularly to find cracks that could exist in the other direction. It is normal part of some QA procedures for certain sample lots of certain parts to go through a MPI to better assess the quality of a batch of parts. BTW the when you get those similarly proofed STAG components in, please be sure to let us know. My shipment of STAG MP tested Bolts are coming in soon (should be next week). BCO is welcome them as well. C4

Will be monitoring your site. This is good news.

Quoted: Quoted: Quoted: Quoted: Quoted: 3)  The Colt proof marks of "MP" - do NOT specifically mean "Magnetic Particle Inspected". "MP" is Colt's proof mark for a process done to both bolts and barrels, to include an HPT (High Pressure Test).   Using a M197 Proof Load cartridge, a round is fired with every barrel and bolt.  The proof load is approx 72K PSI (USGI ammo runs approx 50-55K).  After the HPT, the barrel and bolts go through a MPI (Magnetic Particle Inspection) , to check for surface cracks and defects that could not be seen by the human eye.  The idea is that the two most critical parts of the rifle system are put under an additional level of stress.  If both barrels and bolts pass HPT / MPI, then it is an indication of the integrity and the quality. I have said this before but (relating to bolts and barrels) to MPI without HPT is almost worthless, and to HPT without then doing the MPI is probably dangerous. Colt's "MP" = HPT + MPI, in that order. MPI is a Non Destructive Test (NDT) that electrically magnetizes the part to be inspected.  The part is then put under a "black type light" and run through a solution that suspends tiny florescent metal particles (usually water based).  Any microscopic surface cracks attract these particles in the area of the crack.  These accumulated particles show up under the lighting as a florescent line.  I have sat in on some MPIs, and when looked at under normal lighting the crack can be completely invisible-- even if you know where to look. MPI when done properly, is done in two directions that run perpendicular from each other.  As it related to a linear object like a barrel, the barrel is magnetize at both muzzle and chamber then inspected and then magnetized circularly to find cracks that could exist in the other direction. It is normal part of some QA procedures for certain sample lots of certain parts to go through a MPI to better assess the quality of a batch of parts. BTW the when you get those similarly proofed STAG components in, please be sure to let us know. My shipment of STAG MP tested Bolts are coming in soon (should be next week). BCO is welcome them as well. C4 Will be monitoring your site. This is good news. Expect the price to be around $56 per bolt. C4

What do the regular ones cost??

More than you ever probably wanted to know about MPI:

FAQ at MAGNAFLUX:
www.magnaflux.com/library/faq_mag.stm

From SAE Document J420 Revised Mar '91 "Magnetic Particle Inspection":
3. General—Magnetic particle inspection is a nondestructive means of inspecting ferromagnetic materials such as iron and steel for discontinuities (cracks, seams, near surface inclusions) by the detection of leakage fields through the use of magnetic particles.  Magnetic particle inspection is an aid to visual inspection of objects. Surface or near surface discontinuities  that might not be seen with the aid of optical magnification are regularly detected in manufacturing operations or maintenance. The process is not applicable to nonmagnetic materials. The usual basic steps in magnetic particle inspection of an object are: clean, magnetize, apply magnetic particles, inspect, and demagnetize.  Post cleaning is frequently done. Magnetic particle inspection is a relatively simple procedure. It is most effective when the various factors, such as types of magnetization, current, particles, equipment, and method, are properly selected for the application.

4. Principle—The principle of magnetic particle inspection is the accumulation of particles due to magnetic flux leakage at discontinuities in a magnetized test object. The material subjected to the inspection is magnetized in a fashion which will produce north and south poles on opposite edges of a discontinuity. Finely divided magnetic particles are introduced into the flux leakage field between the poles, and are held there by the magnetic leakage flux. The visible accumulation of these particles is called an indication.

5. Procedure—A magnetic field is induced in the part to be tested by the application of an electric current through the part, or through a central conductor inserted through a hole in the part, or by means of a yoke, prods, or coil. The type of magnetization selected is determined primarily by the need to establish magnetic flux lines perpendicular to the direction of anticipated surface imperfections. Any discontinuity at or near the surface of the part will interrupt the magnetic flux induced in the part and a leakage field will be formed at the surface of the part. Magnetic particles in the vicinity of this leakage field will be attracted to it, forming a visible indication which, to experienced interpreters, expresses the characteristics of the discontinuity. Following the creation of the indication, the interpretation of the indication, and the evaluation of the discontinuity, the part is suitably demagnetized and, where required, cleaned.

Adequate light must be provided for the quick and sure detection of the indications of discontinuities. Lights should be adjusted to give broad highlights on finished machine parts. If fluorescent lighting is used, the tubes should be located transverse to the long axis of the parts being inspected. A nominal illumination level of 108 1x (100 ft-c) of white light should be present on the part surface in the case of nonfluorescent inspection.  Personnel should have eyesight, corrected or uncorrected, capable of distant vision of 20/30 in at least one eye and should be able to read Jaeger Type No. 2 with both eyes at 305 mm (12 in).

An adequate source of long wave ultraviolet light (approximate 3650 Å, colloquially known as black light) must be provided for inspection when using the flourescent magnetic particle inspection method. A filtered highpressure mercury vapor source is generally recommended. The emitted light should have an intensity of 97 1x (90 ft-c) at a 380 mm (15 in) distance from the source, or no less than 140 mW cm2 (900 mW in2) on the part surface. For detection of certain fine indications, illumination at the part surface may need to be as high as 270 1x (250 ft-c). Personnel vision requirements are the same as for nonfluorescent inspection, but in addition, visual acuity in the green-yellow spectrum must be satisfactory.

Demagnetization consists of removing objectionable residual magnetic fields from parts which have been subjected to magnetic particle inspection. This must be done to prevent the deflection of adjacent sensitive instruments and to prevent the attraction of small magnetic chips, or the like, which could cause damage to contacting surfaces. The most common type of demagnetization consists of drawing the magnetized part through a high intensity alternating current solenoid. Another type, often used on heavier parts, consists of passing an alternating current or reversing direct current through the part or through a surrounding solenoid, and then gradually reducing the current value to near zero. Demagnetization is sometimes effected in subsequent processing, such as heat treatment, or hot washing, of a part. Effectiveness of the demagnetizing is usually determined through use of inexpensive meters made for this purpose.  Irons and steels exhibit magnetic characteristics which vary with hardness and composition. Continuous magnetization during particle application is used on relatively soft steels since they usually do not retain sufficient magnetism to allow the use of the residual method. These steels are processed for inspection by introducing the magnetic particles into the leakage fields created at the discontinuities while the magnetizing force is present. Parts processed in this way are said to be processed by the continuous method. Use of the continuous method makes possible the successful inspection of irons and steels which do not retain sufficient magnetism for processing by the residual method. In addition to this, certain subsurface discontinuities are easily detected in both hardened and unhardened parts by this method when direct current magnetization is employed.

The residual magnetization test method may be applied to hardened steels, and other highly retentive materials, since they will retain magnetism after the force has been removed. These remaining magnetic fields will produce leakage fields adjacent to discontinuities strong enough to hold magnetic particles and produce indications. Parts processed through the use of these retained fields are said to be processed by the residual method. Use of the residual method often eliminates nonrelevant indications. It is especially useful for the detection of surface discontinuities in hardened parts. An adequate level of magnetization is required.

Wet particles used in suspension liquid usually consist of finely ground magnetic iron oxide. These particles are coated so they can be easily dispersed in a liquid vehicle. They are generally available in powder form having red or black nonfluorescent colors. They are also available coated with a material which fluoresces under long wave ultraviolet (black) light. Wet particles are commonly used in maintenance, process, and finish inspection of machine and engine parts. The wet process offers the advantage of ease of application of the particles, sensitivity in locating the finest discontinuities, and, especially with the fluorescent particle, rapid inspection rates.

Dry particles consist of finely divided magnetic material in powder form. These particles are coated so as to be easily conveyed by air to the part being inspected. They are generally available in many colors for maximum contrast with the test object. Dry particles are commonly used for the maintenance, process, and finish inspection of heavy weldments, heavy castings, and heavy forgings. Dry particles are superior for the inspection of very rough surfaces and for the location of subsurface discontinuities in rough castings, forgings, and weldments.

Circular magnetization consists of inducing a circular magnetic field in a part so that the magnetic lines of force take the form of concentric rings about the axis of the current. This is accomplished by passing the current directly through the part, or by passing the current through a conductor which passes through a hole in the part, sometimes by use of prods. The circular method is used chiefly to indicate discontinuities radiating from and parallel to the axis of the current flow.

Longitudinal magnetization consists of inducing a longitudinal magnetic field in a part by making it the core of a solenoid, such as placing it in a coil or by making it a link in a magnetic circuit through use of a yoke. In a part so magnetized, the lines of force will be parallel to the axis of the solenoid, and the part will exhibit the properties of a bar magnet. The longitudinal method is used to indicate discontinuities transverse or circumferential to the long axis of a part.

Moving field magnetization consists of inducing fields in a part in more than one direction almostsimultaneously. The fields induced may be a combination of circular and longitudinal or may be a combination of either type. The moving field method may be used on many parts ordinarily requiring two or more distinct magnetization and inspection operations. The moving field method, because of the rapidly changing field directions, makes possible the location of all detectable discontinuities after only one processing. This may, in some cases, eliminate a great percentage of the time required for the inspection if the parts were processed by more conventional methods.

Alternating current magnetization is commonly used for moderately stressed parts in production and for the detection of fatigue discontinuities due to service. Alternating current magnetization is always equal to, and often superior to, direct current magnetization for the detection of surface discontinuities. Subsurface discontinuities are not revealed when alternating current is used. In moderately stressed parts, this greatly simplifies inspection.

Direct current magnetization is commonly used for highly stressed parts. It is able to disclose certain subsurface discontinuities in addition to surface discontinuities.

Half-wave direct current is commonly used in the inspection of heavy weldments, heavy castings, and heavy forgings, in conjunction with dry magnetic particles. Half-wave direct current is essentially a pulsating direct current. The pulsations impart mobility to the magnetic particles, thereby assisting in aligning them in the weaker leakage fields produced by subsurface discontinuities. Subsurface discontinuities are best revealed by the use of this type current.

Quoted: Quoted: Quoted: Quoted: Quoted: Quoted: Quoted: 3)  The Colt proof marks of "MP" - do NOT specifically mean "Magnetic Particle Inspected". "MP" is Colt's proof mark for a process done to both bolts and barrels, to include an HPT (High Pressure Test).   Using a M197 Proof Load cartridge, a round is fired with every barrel and bolt.  The proof load is approx 72K PSI (USGI ammo runs approx 50-55K).  After the HPT, the barrel and bolts go through a MPI (Magnetic Particle Inspection) , to check for surface cracks and defects that could not be seen by the human eye.  The idea is that the two most critical parts of the rifle system are put under an additional level of stress.  If both barrels and bolts pass HPT / MPI, then it is an indication of the integrity and the quality. I have said this before but (relating to bolts and barrels) to MPI without HPT is almost worthless, and to HPT without then doing the MPI is probably dangerous. Colt's "MP" = HPT + MPI, in that order. MPI is a Non Destructive Test (NDT) that electrically magnetizes the part to be inspected.  The part is then put under a "black type light" and run through a solution that suspends tiny florescent metal particles (usually water based).  Any microscopic surface cracks attract these particles in the area of the crack.  These accumulated particles show up under the lighting as a florescent line.  I have sat in on some MPIs, and when looked at under normal lighting the crack can be completely invisible-- even if you know where to look. MPI when done properly, is done in two directions that run perpendicular from each other.  As it related to a linear object like a barrel, the barrel is magnetize at both muzzle and chamber then inspected and then magnetized circularly to find cracks that could exist in the other direction. It is normal part of some QA procedures for certain sample lots of certain parts to go through a MPI to better assess the quality of a batch of parts. BTW the when you get those similarly proofed STAG components in, please be sure to let us know. My shipment of STAG MP tested Bolts are coming in soon (should be next week). BCO is welcome them as well. C4 Will be monitoring your site. This is good news. Expect the price to be around $56 per bolt. C4 What do the regular ones cost?? About $10-15 less. C4

At that price, I'll be in for a couple.

This is obviously NOT a question we can answer here. No one knows what Colts' failure rate is. Nor do we know what the 'field' failure rate is for these tested parts. We also don't know the 'field' failure rate for non-tested parts. Are the two rates vastly dissimilar?

So, there is no way of knowing how beneficial this testing is - if at all. Don't misinterpret what I'm saying. I'm not saying it does no good, simply that we have no way of knowing or showing that it does or doesn't. Colt may know this. If so, that is what they should use in their advertising - not just say how they are doing the testing.

As has already been mentioned, the .gov requires this testing. I'm sorry, but that doesn't tell me anything about it's relavance. The .gov requires alot of things that I believe are monumentally ineficient. So, that's not a very sound argument, if you ask me. No one is claiming that since Colt tests these parts that they never fail in the field. That would be silly. Maybe they fail less often than non-tested parts. It would just be interesting to know what margin of reliability (if any) the extra cost buys you.

If that's the case, then the testing may actually be beneficial. I'm just saying, aside from the anecdotal evidence you mentioned, I don't have any numbers to show anyone. And it seems no one else does either.

I don't have access to the rejection statistics or failure rates.

However I think the bottom line is, without proofing, it's a crap shoot. You may get a good bolt/barrel, or you may not. The 3 questions you have to ask are:

1) can you afford to pay for the proofed component
2) How important is it that your components be consistent and
2) are you a gambling man.

Why is McDonald's so successful? They are surely not the best burger out there, but in general they are consistent. A big Mac in Newark tastes much like a Big Mac in Dallas. They have QC that ensures this. This is also what proofing does for Colt and other military contractors like FN Herstal. A more predictable outcome, that is what the Military and LE need in order to be able to plan and accomplish their missions.

As a civilian do you care whether or not your Big Macs all taste the same? It's entirely up to you.
But I know when I had 40 men under my command, all armed with M16s that were mission cirtical, I needed to to know they would wear/break in a consistent manner so I could plan the logistical and tactical needs of my unit. Later as XO the logistical nightmares became my main job, and my Co armorers came to me with their requests for new components. Bolt failures were not all that common, maybe 1 or two a year, with normal training and range time. But it was fairly consistent over time.

That is what the proofing does for you.

Hey Grant,


Are LMT Bolts and carriers tested in this manner?  And do you have any in stock?

Thanks

I wonder if Stickman still has the photos of those three, proofed, and broken Colt bolts. Not one, or two, but three. With the way Colt's proofing methods are praised one would think it is impossible for any one person to have in their possesion one busted Colt bolt, let alone three

Riddle me this, if proofing is such a safe measure that reduces the odds of critical failure, how did stick get three of them. Bad luck? Or are you going to accuse the least biased and one of the most standup members on this site of lying or having an agenda

Quoted: ... The Military requires it because they want to limit the chance of a bolt breaking. Guys that run carbine classes (like the 10-8 guys) see broken bolts and from what I understand they are NOT Colt bolts. C4

+1
I have read multiple AARs that documented bolt failures in training of both Bushmaster, DPMS, and others.  This doesn't mean that a Colt or other proof/MP-tested bolt won't break, as they do have a limited life, but the QC and testing helps to ensure that you won't have a premature failure at the worst-possible moment.  Murphy will prevail.

Do you keep those MPI Stamped LMT bolts in stock, or that a special order item.

Quoted: I wonder if Stickman still has the photos of those three, proofed, and broken Colt bolts. Not one, or two, but three. With the way Colt's proofing methods are praised one would think it is impossible for any one person to have in their possesion one busted Colt bolt, let alone three Riddle me this, if proofing is such a safe measure that reduces the odds of critical failure, how did stick get three of them. Bad luck? Or are you going to accuse the least biased and one of the most standup members on this site of lying or having an agenda

AR-15 bolts have been problematic starting in the mid 1960's with the introduction of ball powder in issue M193 ammo.  Since then magnetic particle testing, carpenter steel, and shot peening have been added to the specs (Proofing from the beginning).  Colt's has developed an improved M4 bolt but the US Army will not accept it, in that the current bolt meets life expectations, and they don't want to introduce a new part into the system.  The general consensus at this point that the M4 bolt is only good for about 20,000 rounds (short gas tube, and ball powder shorten it's life).  Note that the bolts in Stickman's picture are well used.

Because the AR-15 has a weak bolt by design such things as making them out of carpenter steel, shot peening, proofing and inspection are more important then in other more stout designs.  Skipping any of these can lead to premature failure, as in a brand new bolt can bust immediately.

Quoted: Quoted: I wonder if Stickman still has the photos of those three, proofed, and broken Colt bolts. Not one, or two, but three. With the way Colt's proofing methods are praised one would think it is impossible for any one person to have in their possesion one busted Colt bolt, let alone three Riddle me this, if proofing is such a safe measure that reduces the odds of critical failure, how did stick get three of them. Bad luck? Or are you going to accuse the least biased and one of the most standup members on this site of lying or having an agenda I don't think there is a need to pick a fight over a couple of Colt bolts getting through the QC process (as this happens to all companies). C4

Not picking a fight, but three busted bolts in one person's possesion should be unlikely to impossible if any one part is scrutinized that hard.

For example. Lets say a person has 20 Colt bolts and three are busted, that's a whooping 15% chance of failure.

The rate of failure should be less than 4% if something is that well proofed and inspected. But then again, no one knows the rate of failure of Colt bolts, at best, you can only speculate, but never validate Colts methods resulting in any measurable gain in bolt life

For example, the Durability of chrome Moly 4140 barrels has been questioned many times on this site. Denny in turn posted test results of 4140 barrels subjected to extreme stress to 18k-20k rounds before blowing up.

Likewise, I'd like to see a CMT, LMT, or RRA compared to a colt bolt and tested till destroyed. The Colt bolt should easily out-live the competing non-MP tested bolts. But I dont think anyone here will go on record and say they believe 100% that the Colt will outperform the others.

Quoted: Quoted: Quoted: I wonder if Stickman still has the photos of those three, proofed, and broken Colt bolts. Not one, or two, but three. With the way Colt's proofing methods are praised one would think it is impossible for any one person to have in their possesion one busted Colt bolt, let alone three Riddle me this, if proofing is such a safe measure that reduces the odds of critical failure, how did stick get three of them. Bad luck? Or are you going to accuse the least biased and one of the most standup members on this site of lying or having an agenda I don't think there is a need to pick a fight over a couple of Colt bolts getting through the QC process (as this happens to all companies). C4 Not picking a fight, but three busted bolts in one person's possesion should be unlikely to impossible if any one part is scrutinized that hard. For example. Lets say a person has 20 Colt bolts and three are busted, that's a whooping 15% chance of failure. The rate of failure should be less than 4% if something is that well proofed and inspected. But then again, no one knows the rate of failure of Colt bolts, at best, you can only speculate, but never validate Colts methods resulting in any measurable gain in bolt life

You could achieve close to 100 percent failure rate with Colt's bolts, just a matter of number of rounds down range.

Quoted: Quoted: Quoted: Quoted: I wonder if Stickman still has the photos of those three, proofed, and broken Colt bolts. Not one, or two, but three. With the way Colt's proofing methods are praised one would think it is impossible for any one person to have in their possesion one busted Colt bolt, let alone three Riddle me this, if proofing is such a safe measure that reduces the odds of critical failure, how did stick get three of them. Bad luck? Or are you going to accuse the least biased and one of the most standup members on this site of lying or having an agenda I don't think there is a need to pick a fight over a couple of Colt bolts getting through the QC process (as this happens to all companies). C4 Not picking a fight, but three busted bolts in one person's possesion should be unlikely to impossible if any one part is scrutinized that hard. For example. Lets say a person has 20 Colt bolts and three are busted, that's a whooping 15% chance of failure. The rate of failure should be less than 4% if something is that well proofed and inspected. But then again, no one knows the rate of failure of Colt bolts, at best, you can only speculate, but never validate Colts methods resulting in any measurable gain in bolt life You could achieve close to 100 percent failure rate with Colt's bolts, just a matter of number of rounds down range.

Exactly, everything man made has a breaking point, but is the breaking point of a Colt bolt higher than the breaking point of a CMT bolt for example. No one here knows the answer, but many say the Colt is superior because of an additional process, without ever really looking at the end result

Based on what little I have found about Stick, he probably sees alot more bolts of any kind than most people here do, excluding the vendors who build/sell stuff like that.  To have three failed Colt bolts doesn't surprise me too much, if you see enough bolts with any appreciable round count on them, you're going to see failures.  

Some here act like Colt is infallable.  Others think nontested equipment is equal to tested and proven equipment.  Both are wrong in one way or another, IMO.

Quoted: I don't have access to the rejection statistics or failure rates. However I think the bottom line is, without proofing, it's a crap shoot. You may get a good bolt/barrel, or you may not. The 3 questions you have to ask are: 1) can you afford to pay for the proofed component 2) How important is it that your components be consistent and 2) are you a gambling man. Why is McDonald's so successful? They are surely not the best burger out there, but in general they are consistent. A big Mac in Newark tastes much like a Big Mac in Dallas. They have QC that ensures this. This is also what proofing does for Colt and other military contractors like FN Herstal. A more predictable outcome, that is what the Military and LE need in order to be able to plan and accomplish their missions. As a civilian do you care whether or not your Big Macs all taste the same? It's entirely up to you. But I know when I had 40 men under my command, all armed with M16s that were mission cirtical, I needed to to know they would wear/break in a consistent manner so I could plan the logistical and tactical needs of my unit. Later as XO the logistical nightmares became my main job, and my Co armorers came to me with their requests for new components. Bolt failures were not all that common, maybe 1 or two a year, with normal training and range time. But it was fairly consistent over time. That is what the proofing does for you.

Consistency? Perhaps. Of course you realize that using consistently crappy products (Big Macs, IMHO) in your argument is not a real winner. Certainly no one is going to say that McD's consistent processes lead to to a "high-quality" burger.

And that is exactly my point.

I operate a business and I fully understand and utilize QAA (Quality Assesment & Assurance) as well as PI (Process Improvement). Often in a a PI meeting, we have to look past the process we are trying to improve to look at whether ANY process can give us the outcome we desire. That is very simply my point. The outcome is all that matters! Even in ARs.

Ask this question; Why not test every part more stringently? Is it because no other parts ever fail? No. Is it because no other failure types cause the weapon not to operate? No. It's because testing has a cost associated with it. All I want to know is whether or not this particular test is woth the $$$. That doesn't make me a gambling man, just a realist. Gambling is knowing the odds and going against them anyway. In this case none of us know the odds!

If we did, this argument would probably go away - naturally.

Quoted: Exactly, everything man made has a breaking point, but is the breaking point of a Colt bolt higher than the breaking point of a CMT bolt for example. No one here knows the answer, but many say the Colt is superior because of an additional process, without ever really looking at the end result

The guys that teach shooting classes see more rounds down range then any other group I am aware of.  There are also a mix of brands used in these classes.  They see busted bolts on a regular basis, and are well aware of how different brand bolts hold up.

Must admit I don't know what a CMT bolt is so won't comment on those.

Quoted: Quoted: I don't have access to the rejection statistics or failure rates. However I think the bottom line is, without proofing, it's a crap shoot. You may get a good bolt/barrel, or you may not. The 3 questions you have to ask are: 1) can you afford to pay for the proofed component 2) How important is it that your components be consistent and 2) are you a gambling man. Why is McDonald's so successful? They are surely not the best burger out there, but in general they are consistent. A big Mac in Newark tastes much like a Big Mac in Dallas. They have QC that ensures this. This is also what proofing does for Colt and other military contractors like FN Herstal. A more predictable outcome, that is what the Military and LE need in order to be able to plan and accomplish their missions. As a civilian do you care whether or not your Big Macs all taste the same? It's entirely up to you. But I know when I had 40 men under my command, all armed with M16s that were mission cirtical, I needed to to know they would wear/break in a consistent manner so I could plan the logistical and tactical needs of my unit. Later as XO the logistical nightmares became my main job, and my Co armorers came to me with their requests for new components. Bolt failures were not all that common, maybe 1 or two a year, with normal training and range time. But it was fairly consistent over time. That is what the proofing does for you. Consistency? Perhaps. Of course you realize that using consistently crappy products (Big Macs, IMHO) in your argument is not a real winner. Certainly no one is going to say that McD's consistent processes lead to to a "high-quality" burger. And that is exactly my point. I operate a business and I fully understand and utilize QAA (Quality Assesment & Assurance) as well as PI (Process Improvement). Often in a a PI meeting, we have to look past the process we are trying to improve to look at whether ANY process can give us the outcome we desire. That is very simply my point. The outcome is all that matters! Even in ARs. Ask this question; Why not test every part more stringently? Is it because no other parts ever fail? No. Is it because no other failure types cause the weapon not to operate? No. It's because testing has a cost associated with it. All I want to know is whether or not this particular test is woth the $$$. That doesn't make me a gambling man, just a realist. Gambling is knowing the odds and going against them anyway. In this case none of us know the odds! If we did, this argument would probably go away - naturally.

Finally someone gets it. Now I wait for the answer, but I dont think I'll get one that addresses your concerns

Quoted: CMT = Continental Machine and Tool. They provide Colt with SOME parts. C4

OK, thanks for the info.  Colt's has numerous venders, never put out any effort to figure out who they are/were.