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Posted: 1/8/2005 9:14:29 PM EDT
Ok, so I know that Stainless Steel barrels are supposed to wear out quicker than say 4140/4150 barrels; but why? I mean isn't SS much harder (rockwell) than 4140/50 stuff? If this is the case then wouldn't it make sense that the stronger/harder metal would last longer? I must be missing something or wrong on my facts. Please explain.
Link Posted: 1/8/2005 9:21:39 PM EDT
Some cartridges are just barrel burners, no matter what type of steel you use.
Link Posted: 1/8/2005 9:37:27 PM EDT
I think most rifle barrel steels are heat treated to around 25-32 RC, whether they are 4140/4150 or stainless (416).
Link Posted: 1/8/2005 9:47:20 PM EDT
Ok, but why is it "common knowledge" that SS stuff doesn't last as long? The reason I am asking is because this just seems to me to be one of those magical facts. Doesn't have to make sense or have a reason. I'm just wondering if this is the case or if there ARE some real reasons as to why?
Link Posted: 1/8/2005 9:48:47 PM EDT
call mythbusters
Link Posted: 1/8/2005 9:53:29 PM EDT
Some things I'm reasonably sure of:

1. chrome lining is detrimental to accuracy in most CL barrels. The theory is that is it applied unevenly due to the process.

2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)

3. chrome lining is harder and more durable than regular CM or stainless steel.

4. stainless match barrels tend to maintain the highest level of accuracy for X rounds. Then they'll typically take a "step down" in accuracy and then continue to degrade over time. Match shooters generally notice the change after X, and then dump the barrel when it's no longer accurate enough.

Link Posted: 1/8/2005 10:13:49 PM EDT
I don't have the facts, but what causes barrel "wear" is more a chemical process than mechanical wear. Crome moly and stainless steel act very differently under different conditions. Hot reducing gasses under very high pressure...

I recall a snippet that chrome moly throat wear is due to small nitrided particles of barrel steel flaking off - the alligatoring look under high magnification. That stuff has different thermal expansion coefficients than the underlaying barrel steel.

If mechanical wear was that much of a problem, barrels would wear out from the muzzle first.

Hot powder gasses are reducing in nature, not oxidizing. You see the fireball effect when those hot reducing gasses see atmospheric oxygen.
Link Posted: 1/8/2005 11:04:21 PM EDT
What pogo said. SS is easier to machine accurately but it doesn't handle temperature changes as well as other types of steel.
Link Posted: 1/8/2005 11:10:37 PM EDT
[Last Edit: 1/8/2005 11:11:14 PM EDT by Boom_Stick]
SS is simply a softer metal that moly or chrome lining. Chrome lining is less accurate in the scope that it will replace your 1/4" group to about 1".

There's no real big difference unless you plan to punch paper for competition. For me the benifits of chrome outweight the teeny tiny setbacks it ads.
Link Posted: 1/9/2005 12:33:37 AM EDT

Originally Posted By Hoplophile:
What pogo said. SS is easier to machine accurately but it doesn't handle temperature changes as well as other types of steel.



What pogo said?!! What the hell did he say? Assuming what you said is true, would you care to explain why a more chemically resistant steel like SS can't handle the heat as well as chrome moly can? Pogo mentioned that it was more chemical. Ok, maybe so. However this doesn't make sense to me since STAINLESS steel doesn't rust like most other steel like 4140. And I'm pretty sure that rusting is a chemical process.

My point is being made right now. Ask a simple question that should have a fairly common sense explaination and I get magical hoo-ha!

Nothing personal guys but this just doesn't add up. I am more than willing to accept that I am STILL wrong, but someone needs to explain it better than this.
Link Posted: 1/9/2005 12:37:06 AM EDT

Originally Posted By Zak-Smith:
Some things I'm reasonably sure of:

1. chrome lining is detrimental to accuracy in most CL barrels. The theory is that is it applied unevenly due to the process.

2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)

3. chrome lining is harder and more durable than regular CM or stainless steel.

4. stainless match barrels tend to maintain the highest level of accuracy for X rounds. Then they'll typically take a "step down" in accuracy and then continue to degrade over time. Match shooters generally notice the change after X, and then dump the barrel when it's no longer accurate enough.




All that sounds very true Zak, but it still doesn't answer my question. If stainless barrels truely do wear out quicker, then exactly what is it that is causing it?
Link Posted: 1/9/2005 12:47:16 PM EDT

Originally Posted By grooVe:

Originally Posted By Zak-Smith:
Some things I'm reasonably sure of:

1. chrome lining is detrimental to accuracy in most CL barrels. The theory is that is it applied unevenly due to the process.

2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)

3. chrome lining is harder and more durable than regular CM or stainless steel.

4. stainless match barrels tend to maintain the highest level of accuracy for X rounds. Then they'll typically take a "step down" in accuracy and then continue to degrade over time. Match shooters generally notice the change after X, and then dump the barrel when it's no longer accurate enough.


All that sounds very true Zak, but it still doesn't answer my question. If stainless barrels truely do wear out quicker, then exactly what is it that is causing it?


I try to add value by precisely stating only the things I "know" and not dillute the discussion with things I'm not personally sure of.

It depends on what you mean by "wear out". Do you mean have a catastrophic rupture? Shoot worse than 2 MOA? Fail a headspace test? Under what shooting conditions? Like shooting High-Power? 3Gun? CQB training? Full auto mag dumps?

An otherwise fine CL barrel might start out shooting 2.5 MOA, while a High-Power shooter may dump his SS match barrel because it now only shoots 1.5MOA after 3000 rounds. Which one is "worn out" ? Either? Both? Neither?

I've read (in an article by Boots Obermeyer) that accuracy degradation under normal wear conditions is mostly a function of throat erosion, and this mirrors experience I've gleaned from local long-range precision shooters (though they aren't shooting AR's).
Link Posted: 1/9/2005 1:17:18 PM EDT

Originally Posted By Zak-Smith:
2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)



Interesting. Is this the consensus? And if so, this means that there is a "best" among manufacturers of AR barrels. Who are they?
Link Posted: 1/9/2005 1:19:19 PM EDT

Originally Posted By heavily_armed:

Originally Posted By Zak-Smith:
2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)


Interesting. Is this the consensus? And if so, this means that there is a "best" among manufacturers of AR barrels. Who are they?


The FN SPR is a bolt-action rifle based on the Winchester Model 70 action.
Link Posted: 1/9/2005 1:23:12 PM EDT
I just thought that SS barrels caused slightly more friction in the barrel from the copper of the bullet.
Which is why I thought that is why SS barrels needed to be cleaned more often than CL

Now... I don't know what the real reason is.
Link Posted: 1/9/2005 1:32:18 PM EDT
I dont know where some of you are getting your information regarding SS to be easy to machine but I assure you its harder to machine than chromoly steel. Unless of course its some kind of SS that I have never cut before. All the SS Ive ever machined has always been a little tougher to machine.

Having said that I would think SS would outlast a plain old chromemoly barrel. Not a chrome lined barrel but just a chromemoly barrel. That chromemoly steel is nothing special at all. ITs cheap and cuts like butter.
Link Posted: 1/9/2005 6:55:59 PM EDT

Originally Posted By Zak-Smith:

Originally Posted By grooVe:

Originally Posted By Zak-Smith:
Some things I'm reasonably sure of:

1. chrome lining is detrimental to accuracy in most CL barrels. The theory is that is it applied unevenly due to the process.

2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)

3. chrome lining is harder and more durable than regular CM or stainless steel.

4. stainless match barrels tend to maintain the highest level of accuracy for X rounds. Then they'll typically take a "step down" in accuracy and then continue to degrade over time. Match shooters generally notice the change after X, and then dump the barrel when it's no longer accurate enough.


All that sounds very true Zak, but it still doesn't answer my question. If stainless barrels truely do wear out quicker, then exactly what is it that is causing it?


I try to add value by precisely stating only the things I "know" and not dillute the discussion with things I'm not personally sure of.

It depends on what you mean by "wear out". Do you mean have a catastrophic rupture? Shoot worse than 2 MOA? Fail a headspace test? Under what shooting conditions? Like shooting High-Power? 3Gun? CQB training? Full auto mag dumps?

An otherwise fine CL barrel might start out shooting 2.5 MOA, while a High-Power shooter may dump his SS match barrel because it now only shoots 1.5MOA after 3000 rounds. Which one is "worn out" ? Either? Both? Neither?

I've read (in an article by Boots Obermeyer) that accuracy degradation under normal wear conditions is mostly a function of throat erosion, and this mirrors experience I've gleaned from local long-range precision shooters (though they aren't shooting AR's).



Zak I knew I could count on you for clear concise comments. They are much appreciated! My previous post was mearly trying to get you (someone) to admit that the generalized statement that SS "wears out" easier doesn't make much sense all by itself. It needs MUCH clarification. Your comments are making my point EXACTLY.

What is "worn out"? Is it when MOA is above a given number, or simply when the barrel is unable to fire. (Wouldn't want to be around for that.) After how many rounds does a barrel wear out? What part of the barrel is being worn? (Throat, rifling, etc)

The point I think you are making is that it's all a matter accuracy.
Based off of your speculation, let me pose the question this way.

If a CL can maintain a large MOA for an extended period of time, while a SS's moa might degrade over time, at what point IF ANY does SS become inferior to CL in terms of moa? I understand that the answer would have to be speculation but that's fine with me. 3000, 5000, 10000, NEVER?

Thanks again Zak.

Link Posted: 1/9/2005 6:58:15 PM EDT

Originally Posted By Zak-Smith:

Originally Posted By heavily_armed:

Originally Posted By Zak-Smith:
2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)


Interesting. Is this the consensus? And if so, this means that there is a "best" among manufacturers of AR barrels. Who are they?


The FN SPR is a bolt-action rifle based on the Winchester Model 70 action.



That rifle has always been on my next to buy list. I really like those guns!
Link Posted: 1/9/2005 8:40:28 PM EDT
[Last Edit: 1/9/2005 8:41:14 PM EDT by Zak-Smith]

Originally Posted By grooVe:
What is "worn out"? Is it when MOA is above a given number, or simply when the barrel is unable to fire. (Wouldn't want to be around for that.) After how many rounds does a barrel wear out? What part of the barrel is being worn? (Throat, rifling, etc)

The point I think you are making is that it's all a matter accuracy.
Based off of your speculation, let me pose the question this way.

If a CL can maintain a large MOA for an extended period of time, while a SS's moa might degrade over time, at what point IF ANY does SS become inferior to CL in terms of moa? I understand that the answer would have to be speculation but that's fine with me. 3000, 5000, 10000, NEVER?


To do this test, we'd need a representative sample of SS and CL barrelled uppers, a firing regimen, dimensional (headspace, freebore, etc) and accuracy testing protocol, and a truckload of ammo (maybe as much as 25k+ PER BARREL). Anybody wants to spot me the ammo, I'd be happy to get some barrels together.

Here are some other points to ponder:

* It doesn't take much to blow up an M4 barrel. That military report said under 500 rounds fired full auto would burst the barrel. At a testing facility, I've seen boxes full of burst barrels, melted gas tubes and handguards. (And they weren't trying to blow them up.)

* A friend of mine has a 16" barrel (which I could have sworn he said was SS) with over 20k or 30k rounds through it. The rifling is gone from the first several inches of the barrel. But it still shoots about a minute with his handloads.

* My JP rifle (20" SS bbl) has probably around 5k rounds through it, including the barrel-burning ITRC-- 550+ rounds in 20 minutes, dunked with water repeatedly to cool. The zero wandered a little bit after that, but once rezeroed, it still shoots better than a minute.

* The average CL barrel probably shoots worse than 1.5 MOA. My 16" CL MRP barrel shoots about 1.9MOA on average with 75gr BH.

* Here is a good article, but it doesn't give us our answer: www.snipersparadise.com/tsmag/june2001.htm (This is the one I was referring to before)
Link Posted: 1/9/2005 8:46:13 PM EDT

Originally Posted By JohnnyMcEldoo:
I dont know where some of you are getting your information regarding SS to be easy to machine but I assure you its harder to machine than chromoly steel. Unless of course its some kind of SS that I have never cut before. All the SS Ive ever machined has always been a little tougher to machine.

Easier to machine to tight tolerances. More specifically easier to bore and rifle to tight tolerances.
Link Posted: 1/9/2005 8:48:26 PM EDT
It has been suggested that the surface characteristics allow SS barrels to "resist" throat erosion longer.

Does this make sense to the metallurgists and machinists here? (I'm neither.)

-z
Link Posted: 1/9/2005 9:00:00 PM EDT

Originally Posted By grooVe:
Assuming what you said is true, would you care to explain why a more chemically resistant steel like SS can't handle the heat as well as chrome moly can? Pogo mentioned that it was more chemical. Ok, maybe so. However this doesn't make sense to me since STAINLESS steel doesn't rust like most other steel like 4140. And I'm pretty sure that rusting is a chemical process.


1. The stainless steel use in barrels will rust, it is jsut more resistant than chrome moly.

2. Most chemical processes work more quickly the more heat is present, and stainless steel doesn't transfer heat as quickly as chrome moly.
Link Posted: 1/9/2005 10:59:37 PM EDT
[Last Edit: 1/9/2005 11:01:09 PM EDT by grooVe]
I read the article Zak. Makes me want to just give up, or just not worry about it.


Quote from Article:
Boots: I don't believe any hard-core scientific tests have been conducted but instead, there are experiences gained over the years by several barrel makers.



You'd think that there would have been ALOT of scientific tests to see what exactly what is happening.

Well, I thank you all for your input. I am now that much more educated! This has definately sparked my interest. I will have to find some more reading material on this. Thanks again guys.
Link Posted: 1/10/2005 12:59:34 AM EDT

Originally Posted By Zak-Smith:

Originally Posted By heavily_armed:

Originally Posted By Zak-Smith:
2. there are some CL barrels that are very accurate (e.g. the CL barrel on the FN SPR sniper rifle)


Interesting. Is this the consensus? And if so, this means that there is a "best" among manufacturers of AR barrels. Who are they?


The FN SPR is a bolt-action rifle based on the Winchester Model 70 action.



Yes, I know.

Let me restate the question: If FN's CL barrel is "very accurate" then which AR CL barrels are "very accurate"? And which is the best?
Link Posted: 1/10/2005 1:47:16 PM EDT

Originally Posted By Hoplophile:

Originally Posted By JohnnyMcEldoo:
I dont know where some of you are getting your information regarding SS to be easy to machine but I assure you its harder to machine than chromoly steel. Unless of course its some kind of SS that I have never cut before. All the SS Ive ever machined has always been a little tougher to machine.

Easier to machine to tight tolerances. More specifically easier to bore and rifle to tight tolerances.



That makes perfect sense now. Chromolly doesnt seem to turn or bore consistantly unless your taking a big cut. SS seems more forgiving.
Link Posted: 1/10/2005 3:10:16 PM EDT

Originally Posted By JohnnyMcEldoo:

Originally Posted By Hoplophile:

Originally Posted By JohnnyMcEldoo:
I dont know where some of you are getting your information regarding SS to be easy to machine but I assure you its harder to machine than chromoly steel. Unless of course its some kind of SS that I have never cut before. All the SS Ive ever machined has always been a little tougher to machine.

Easier to machine to tight tolerances. More specifically easier to bore and rifle to tight tolerances.



That makes perfect sense now. Chromolly doesnt seem to turn or bore consistantly unless your taking a big cut. SS seems more forgiving.



+1 and I would like to know which CL AR barrels are very accurate like the FN stuff too.
Link Posted: 1/11/2005 2:14:03 AM EDT
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