Be an informed consumer!

[1371marine]

Couldn't have said it better myself. What people need to know is exactly what you said, "it's a minimum requirement" As far as the certs offered by a company to back their products...Well some are exactly like the "milspec toilet paper" . Having worked in quality control for the last 10 years, I've seen a hell of a lot of companies/suppliers try to pass off generic certs to cover their ass. One could only assume that a reputable company, like some of the ones mentioned, would be giving you a legitimate certification or testing report. Even with that said, you'd darn near have to be a metallergist to read the steel reports and at least have some background in NDE (non destructive examination) to read and understand the test reports. In addition you'd have to be familiar with steel properties like yield strengths, elasticity and the like to understand the proof testing. Furthermore, performance based testing, is in essence just another claim backed by a piece of paper which can also be fudged. It is the better of the two choices when it comes to making an informed decision about a purchase. Although the only way for a company to truly back their claims, tests, reports etc... would be to sell it with an UNCONDITIONAL, NO QUESTIONS ASKED, WE'LL SHIP YOU A NEW ONE TODAY SIR, SORRY FOR YOUR TROUBLES WARRANTY. That said, it would support and validate their pricing because like mentioned before those tests aren't cheap. In closing, it is best to become familiar with some of the background needed to understand those reports if you're going to ask for one. Educate yourself, do the research and become an informed consumer.
Semper Fi......

Love this post. Puts the "TDP" and "MILSPEC" in its proper perspective. Something to be exceeded. IMO the TDP and the sweet no-competition deal Colt got from the government hurt them as free market competitors and it shows now.

Not sure if this was already covered... the thread started out talking about MilSpec and seems to have degraded into a dick measuring standard.

The "MilSpec" exists to protect Uncle Sam's investment - to make sure that the 10,000 barrels he is buying are the same as the two sample barrels that were tested - that said, it is an antiquated system and a lot of folks on both sides of the purchasing would like to see the move to "performance based standards."

Simply put, rather than tell the manufacturer: "you will make your barrels from X steel, and plated them with Y to a standard of 234... blah, blah, blah" - many people would be much happier with a performance standard... something like: "the barrels will have this accuracy standard, they will withstand this pressure, this environmental corrosion test, and heat to XXXX, and will have a service life of XXXX number of rounds without accuracy degrading to worse than XXXXX - and we don't give a shit how you do it."

A performance based requirement allows for innovation and competition... the classic example is the space program - the requirement was "get to the moon... couldn't begin to tell you how you will do it, no one has ever done it"

There are already waivers in specifications to allow for end performance acceptance... and often they result in improved products.

Bottom line is the MilSpec is a standard... the best? No, but it is a standard that allows the purchaser (you) to at least know what they are getting... but in many cases there are things that do not meet the MilSpec, but are actually better products; anyone that has ever wiped their ass with MilSpec toilet paper can attest to that.

[Doc Safari]

Having worked in quality control for the last 10 years, I've seen a hell of a lot of companies/suppliers try to pass off generic certs to cover their ass. One could only assume that a reputable company, like some of the ones mentioned, would be giving you a legitimate certification or testing report. Even with that said, you'd darn near have to be a metallergist to read the steel reports and at least have some background in NDE (non destructive examination) to read and understand the test reports. In addition you'd have to be familiar with steel properties like yield strengths, elasticity and the like to understand the proof testing. Furthermore, performance based testing, is in essence just another claim backed by a piece of paper which can also be fudged.

LOL. I used to work for a company that would use one set of legitimate certs as proof of quality on items from multiple sources. I'm only willing to say so publicly because the company got caught doing it and paid the price long ago.

It just goes to show: paper certifications are still trumped by a company's trusted reputation.

That's why every time someone on this board tells the world what an upstanding guy Paul from BCM is I breathe a sigh of relief that my AR's are Bravo Company.

[1371marine]

Love this post. Puts the "TDP" and "MILSPEC" in its proper perspective. Something to be exceeded. IMO the TDP and the sweet no-competition deal Colt got from the government hurt them as free market competitors and it shows now.

LOL. I used to work for a company that would use one set of legitimate certs as proof of quality on items from multiple sources. I'm only willing to say so publicly because the company got caught doing it and paid the price long ago.

It just goes to show: paper certifications are still trumped by a company's trusted reputation.

That's why every time someone on this board tells the world what an upstanding guy Paul from BCM is I breathe a sigh of relief that my AR's are Bravo Company.

Case in point!! My sentiments exactly. Go with a reputable company and let others know who it is and also which ones to stay away from. P.S. I hope that company wasn't a weapons manufacturer

[sinister]

The "MilSpec" exists to protect Uncle Sam's investment - to make sure that the 10,000 barrels he is buying are the same as the two sample barrels that were tested - that said, it is an antiquated system and a lot of folks on both sides of the purchasing would like to see the move to "performance based standards."

Simply put, rather than tell the manufacturer: "you will make your barrels from X steel, and plated them with Y to a standard of 234... blah, blah, blah" - many people would be much happier with a performance standard... something like: "the barrels will have this accuracy standard, they will withstand this pressure, this environmental corrosion test, and heat to XXXX, and will have a service life of XXXX number of rounds without accuracy degrading to worse than XXXXX - and we don't give a shit how you do it."

A performance based requirement allows for innovation and competition... the classic example is the space program - the requirement was "get to the moon... couldn't begin to tell you how you will do it, no one has ever done it"

The MILSPEC already does this.

This dictates what M4s have to pass for acceptance (it doesn't say squat about individual parts and dimensions -- the drawings and prints do that): http://www.ar15.com/content/webPDF/m4a1milspec.pdf

The TDP and drawings dictate materials and dimensions. MIL-W-13855 outlines general performance-based weapon specs.

[LRRPF52]

Love this post. Puts the "TDP" and "MILSPEC" in its proper perspective. Something to be exceeded. IMO the TDP and the sweet no-competition deal Colt got from the government hurt them as free market competitors and it shows now.

Since most companies don't really care about and can't meet the existing TDP, don't have the engineers to understand and interpret the TDP, I have a very difficult time seeing how they will exceed it.

We've seen this happen over the years. Company X starts up thinking they are going to make it big in the AR15 world by doing something better, which would be a good thing if they actually did, but then...

They focus on the receivers and a BCG coated in NiB, don't know much about barrels, but think stainless or Melonited/QPQ/Nitrided barrels will be some type of magic answer, and make attempts to smash together parts and components that they feel are better, but have no clue as to the materials science or design constraints of the AR15 and AR10.

Some of them sourced already case hardened 8620 barrel extensions, for example. What to do to make them "better"? Send them out for heavy nitriding, which through-hardened the feed lips and leaves serious questions about the ductility of the teeth, where some pretty extreme stresses are being exerted. I was polishing the feed ramps on one such barrel the other day, and the thin edge of the feed ramp literally shattered off like glass. I've never seen that happen before over years of working on AR's. A rubber Cratex bit has never done that on feed ramps in my experience, and it made me have serious reservations about the barrel as a pressure containment vessel.

What I have seen over the years is that almost everybody takes short cuts with parts, and those that think they are "exceeding the Mil-spec", are often trudging far into murky waters with no materials science background, limited to no engineering capabilities, and are going by what they think is a better process, material, or assembly method, that isn't backed by a comprehensive testing program.

The problem is that the bulk of the consumer market doesn't shoot their rifles enough to ever find out where the guns will fail, and companies have been getting away with cranking out garbage, but with a nice package on it, whiz bang coatings, and billet receivers in some cases. Throw in the correct buzzwords to impress Joe consumer, and you'll have plenty of sales volume to justify your trek into unfamiliar waters. These companies need to start crawling before they can walk.

As for me, I don't buy off-the-shelf guns anymore because of trust. I can't trust most people to use a solid reamer, line it up concentrically, or get a gas port diameter right, let alone their shortcuts on springs, detents, barrel extensions, BCG's (this is one area where we have seen improvement, but still not to the same certs that only a handful hold themselves to), etc.

[constructor]

"LRRPF52-Since most companies don't really care about and can't meet the existing TDP, don't have the engineers to understand and interpret the TDP, I have a very difficult time seeing how they will exceed it.

We've seen this happen over the years. Company X starts up thinking they are going to make it big in the AR15 world by doing something better, which would be a good thing if they actually did, but then...

They focus on the receivers and a BCG coated in NiB, don't know much about barrels, but think stainless or Melonited/QPQ/Nitrided barrels will be some type of magic answer, and make attempts to smash together parts and components that they feel are better, but have no clue as to the materials science or design constraints of the AR15 and AR10.

Some of them sourced already case hardened 8620 barrel extensions, for example. What to do to make them "better"? Send them out for heavy nitriding, which through-hardened the feed lips and leaves serious questions about the ductility of the teeth, where some pretty extreme stresses are being exerted. I was polishing the feed ramps on one such barrel the other day, and the thin edge of the feed ramp literally shattered off like glass. I've never seen that happen before over years of working on AR's. A rubber Cratex bit has never done that on feed ramps in my experience, and it made me have serious reservations about the barrel as a pressure containment vessel.

What I have seen over the years is that almost everybody takes short cuts with parts, and those that think they are "exceeding the Mil-spec", are often trudging far into murky waters with no materials science background, limited to no engineering capabilities, and are going by what they think is a better process, material, or assembly method, that isn't backed by a comprehensive testing program.

The problem is that the bulk of the consumer market doesn't shoot their rifles enough to ever find out where the guns will fail, and companies have been getting away with cranking out garbage, but with a nice package on it, whiz bang coatings, and billet receivers in some cases. Throw in the correct buzzwords to impress Joe consumer, and you'll have plenty of sales volume to justify your trek into unfamiliar waters. These companies need to start crawling before they can walk.

As for me, I don't buy off-the-shelf guns anymore because of trust. I can't trust most people to use a solid reamer, line it up concentrically, or get a gas port diameter right, let alone their shortcuts on springs, detents, barrel extensions, BCG's (this is one area where we have seen improvement, but still not to the same certs that only a handful hold themselves to), etc. " end quote Paul

Remember what I said about facts Paul?
Barrel extensions should be carburized to a depth of .010-.015" at a temp of 1550 degrees according to the mil spec.
Meloniting processes range from 900-1075 degrees.

Meloniting an already carburized piece of 8620 actually reduces the hardness of the 8620 part by 1-5 points rockwell.
The hardest Melonite surface is only .0004-.0008" deep(that is 1/8th-1/6th as thick as a piece of copy paper). After that it slowly gets softer. It isn't 70C on the surface and then immediately turn to butter.
The Melonited surface is so thin a traditional hardness tester will not pick it up. A micro tester is needed to test the surface. The diffusion zone under the surface is .004-.008" thick which reaches half depth of the barrel extensions carburized depth. A material that has been carburized by gas or liquid as in Melonite has a hard surface that gradually gets softer as it reaches the center. The core of the object remains tough and ductile not brittle like the through hardening you speak of. That is the whole reason for carburizing.
Reading material for those that want to learn the truth about Melonite- http://www.burlingtoneng.com/melonite.html
Read the paragraph under fig6- http://books.google.com/books?id=m-S...0steel&f=false

[LRRPF52]

From the link mentioned above:

Melonite™ and Melonite QPQ™ are thermochemical processes intended for the case hardening of iron based metals. These processes are categorized as molten salt bath ferritic nitrocarburizing. During these processes, nitrogen, carbon, and small amounts of oxygen are diffused into the surface of the steel, creating an epsilon iron nitride layer (e - FexN).

So if a process results in through hardening of the barrel extension, there's a problem. The barrel extension I was polishing with a rubber Cratex bit shattered, just like a through hardened part, and I had just barely started polishing it.

The biggest question as an informed customer to me is, does the shop know what they are doing, or have they jumped on a bandwagon without knowing all the materials science behind the process, are they using the correct process for the application, and do they know what major blunders to avoid based on a solid understanding of firearms specific requirements.

With a lot of the old coatings and processes being introduced as something new, since there have been new tweaks to them, a shop should know exactly how to spec their parts out before taking a jump. We've seen this now with TiN, NiB, QPQ nitrocarburizing methods, and chrome lining, where a lot of new arrivals to the industry learn the hard way that they don't know what they are doing.

So how does a customer navigate through all this information and know who is GTG, and who isn't? Threads like these can help, but very few will ever see them, unfortunately.

[constructor]

From the link mentioned above:



So if a process results in through hardening of the barrel extension, there's a problem. The barrel extension I was polishing with a rubber Cratex bit shattered, just like a through hardened part, and I had just barely started polishing it.

The biggest question as an informed customer to me is, does the shop know what they are doing, or have they jumped on a bandwagon without knowing all the materials science behind the process, are they using the correct process for the application, and do they know what major blunders to avoid based on a solid understanding of firearms specific requirements.

With a lot of the old coatings and processes being introduced as something new, since there have been new tweaks to them, a shop should know exactly how to spec their parts out before taking a jump. We've seen this now with TiN, NiB, QPQ nitrocarburizing methods, and chrome lining, where a lot of new arrivals to the industry learn the hard way that they don't know what they are doing.

So how does a customer navigate through all this information and know who is GTG, and who isn't? Threads like these can help, but very few will ever see them, unfortunately.

Are you saying you think case hardening is through hardening?
I don't know anyone stupid enough to through harden an extension. There aren't many companies that make extensions to begin with. AO, and CMT probably make most of the barrel extensions. Melonite is a case hardening process just like it says above.

"Case hardening or surface hardening is the process of hardening the surface of a metal object while allowing the metal deeper underneath to remain soft, thus forming a thin layer of harder metal (called the "case") at the surface."

I've read where Bill Alexander said that the mil spec says specifically not to Melonite bolts. That is true you can't only Melonite a bolt and expect it to be strong enough because the case hardening does not go deep enough. If the bolt is gas carburized first then it will be strong enough. I don't think anyone has done an endurance test to see if a bolt will hold up after Meloniting a bolt that was gas carburized first.
The fact that a very thin layer(.0004-.0008") after meloniting is hard(60-70 rockwell) and then starts getting softer for a depth of .004-.008" Then it runs into the 58-60C hardness of the gas carburized piece until the depth reaches .010-.015 deep. At that point the original hardness from gas carburizing gets softer until it reaches the core and a hardness of 48-53C when talking about 8620.
Melonited 4140 and 4150 Barrels are 60-70C on the surface and gradually get softer to the center where they are the machined hardness of IIRC 38-42C.

NiB is a low temp process that will not effect the harness at all. TiN, TiCN, TiAlN are higher temp coating we use on carbide cutting tools but they do not approach a temp high enough to hurt the case hardening created by gas carburizing. Those processes may drop the hardness of a gas carburized part by 1 point Rockwell. TiAlN is off the Rockwell C scale. Harder than Carbide and last 3-10 times longer than uncoated carbide. I treated 200 carriers in 2010 with the stuff. Great coating but it wasn't worth the aggravation dealing with the Ca based company I used to do it.

Re Melonite-The one thing I know of that can cause trouble is if the company that is having the barrel produced does not know that the barrel extensions MUST be torqued after the melonite process. Then the gas port must be drilled after the extension is torqued. Some people think they can just drill the barrel extension alignment pin hole into the threads of the barrel and drive a pin in. If the extension is loose to begin with because of the Melonite treatment all they are doing is pinning the extension on loose. The constant pounding on the threads will compress the threads and loosen the extension further. Accuracy will be poor and get worse.

One process I am not sure of, I haven't dug into it. One company gas carburizes stainless barrels. Stainless in general is weaker than CMV and brittle, especially if the heat treat is done in a certain temp range(# Tempering of 416R steel at temperatures of 400 to 580°C (750-1060F)should be avoided due to low impact resistance). I'm not sure if the gas carburizing adds toughness and strength to the stainless or makes it more brittle. I have shot a few of the barrels. The surface hardness must be 80+, a file would not touch it and a grinding wheel had a tough time.

[LRRPF52]

LRRPF52: So if a process results in through hardening of the barrel extension, there's a problem.

That's what I said, and of course I know the difference between case hardening and through hardening. The extension that shattered the lip off appears to be through hardened in that thin area. Other extensions will only gall in that area at worst. This is the first time I have seen that happen.

What I've gathered from watching the Melonite/QPQ/Nitrocarburizing processes is that there is a compromise of sorts going on, and it all revolves around the barrel extension and gas port, aside from the metallurgy of the steels.

Since extensions are usually 8620 and case hardened, they will take deposition of nitrogen in a different way. The obvious question is, do I send barrels by themselves to be nitrided, or do I send them with the extensions attached?

If someone is sending them attached with the gas ports cut already, it's because they want nitriding in the port to reduce port erosion, but then there is the problem with surface geometry changing at the microscopic level enough to affect torque in the threads.

If a barrel maker doesn't know what they are doing, they might just be sending out pipes for nitriding with the already case-hardened extensions attached, but the process for the nitriding is geared towards the specific metallurgy of the barrel, which is going to be 4140 most of the time.

It leads us back to the original topic: How do I as a consumer know if the company is riding a trend without engineering know how, and how do I know if my extension or barrel is treated properly? One of the first things I noticed when Superior Barrels entered the market was that they specifically mentioned their barrels were not full auto rated.

Then I came across the paper from the 1950's where Army Ordnance tested barrels that had been nitrided, hard chrome lined, and even NiB treated, specifically looking at full auto endurance. Hard chrome lining had the best performance, resisting high heat and repeated shock forces better than the others.

This topic is important to me because I shoot a lot in extreme cold, where we push the material properties of steel in a state that is often more brittle. I'm not talking about going out and plinking on the weekend either in December. There are serious, regionally-significant aspects of this that are important to me and others. I know that MIL-B-11595E holds up well in extreme cold, high volume.

[constructor]

That's what I said, and of course I know the difference between case hardening and through hardening. The extension that shattered the lip off appears to be through hardened in that thin area. Other extensions will only gall in that area at worst. This is the first time I have seen that happen.

What I've gathered from watching the Melonite/QPQ/Nitrocarburizing processes is that there is a compromise of sorts going on, and it all revolves around the barrel extension and gas port, aside from the metallurgy of the steels.

Since extensions are usually 8620 and case hardened, they will take deposition of nitrogen in a different way. The obvious question is, do I send barrels by themselves to be nitrided, or do I send them with the extensions attached?

If someone is sending them attached with the gas ports cut already, it's because they want nitriding in the port to reduce port erosion, but then there is the problem with surface geometry changing at the microscopic level enough to affect torque in the threads.

If a barrel maker doesn't know what they are doing, they might just be sending out pipes for nitriding with the already case-hardened extensions attached, but the process for the nitriding is geared towards the specific metallurgy of the barrel, which is going to be 4140 most of the time.

It leads us back to the original topic: How do I as a consumer know if the company is riding a trend without engineering know how, and how do I know if my extension or barrel is treated properly? One of the first things I noticed when Superior Barrels entered the market was that they specifically mentioned their barrels were not full auto rated.

Then I came across the paper from the 1950's where Army Ordnance tested barrels that had been nitrided, hard chrome lined, and even NiB treated, specifically looking at full auto endurance. Hard chrome lining had the best performance, resisting high heat and repeated shock forces better than the others.

This topic is important to me because I shoot a lot in extreme cold, where we push the material properties of steel in a state that is often more brittle. I'm not talking about going out and plinking on the weekend either in December. There are serious, regionally-significant aspects of this that are important to me and others. I know that MIL-B-11595E holds up well in extreme cold, high volume.

Superior barrels are gas nitrided stainless like I was talking about earlier, just didn't want to throw their name out there because I haven't researched it enough to say it's bad. That is why they aren't full auto rated.
If you know melonite is a case hard then why were you talking about through hardening and being brittle? What process results in through hardening that you keep highlighting? If anything it was the original case hardening to a depth of .010-.-015" since that spec is thicker than the Melonite can harden.
This is a quote from your first post-"Some of them sourced already case hardened 8620 barrel extensions, for example. What to do to make them "better"? Send them out for heavy nitriding, which through-hardened the feed lips and leaves serious questions about the ductility of the teeth, where some pretty extreme stresses are being exerted. I was polishing the feed ramps on one such barrel the other day, and the thin edge of the feed ramp literally shattered off like glass. I've never seen that happen before over years of working on AR's. A rubber Cratex bit has never done that on feed ramps in my experience, and it made me have serious reservations about the barrel as a pressure containment vessel."
What is "heavy nitriding"? Show us a photo of this extension. Surely if you have photos of Dutch made AR10 buffers from 1965 you took a photo of this junk extension. What makes you think the Melonite through hardened the extension? I can understand someone thinking if you stick a piece of steel in a furnace and harden it then you stick it back in it would make it more doner like a chicken in an oven but that isn't the way it works. As I explained in the post above Meloniting an already hard piece of 8620 makes the piece softer by 1-5 points Rockwell.

As far as the Melonite treatment of 2 kinds of steel at the same time we're talking about alloys with .4-1 percent chromium not stainless that has 12-30%. 8620 and 4140 or 4150 at the same time only results in a deeper depth of case for each steel. The diffusion layer for both during Melonite would still be apx .006" which is thinner than the original case hardness depth spec of .010-.015".

Sending separate? Get 200 barrels made cut where the headspace is correct. Remove the extensions and send the barrels out for heat treat. Plan on stamping every single barrel and extension and then mating them back up when they come in?

Post that report from the 50s about the tests. Was it nitrided, carburized or Melonite?

I've seen several military tests that included Nitrided barrels in 50 cal and 30mm. They must be using Nitrided barrels for some things.