School me on steel....

[Bob Shaver]

So I'm confused. I can buy a barrel in 4142 chrome-moly, 416 stainless, 4140 chrome-moly, chrome vandamium, 410 stainless with chrome or melonite linings etc.

What advantages are offered by various steels regarding accuracy and barrel life?

Do you prefer a chrome lined or melonite lined barrels or plain old stainless?

Class is in session.

 

[Mike_Honcho]

What is the purpose of the barrel and what caliber?

You can google the differences and read about carbon / vanadium / fairy dust content and depending on application yes those things can make a difference.

Related to accuracy, the chambering, straightness of the bore, land and groove type, number thereof, lapping thereof are more important than the type of steel. That said, most folks have very good luck with single point cut rifle barrels from known blank sources and chambered by real pros - many of whom roll through this board.

 

[Captain Kirk]

4140R, 416R steel non lined for precision rifle barrels is a good start. Most fine barrel mfrs choose not to use any coatings or linings in the bore.

 

[DT1]

My understanding is that the original purpose for lining a barrel with chrome was to increase their longevity when fired on full auto or at a high rate. The chrome helps protect the rifling and prolongs barrel life. Side benefits of chrome lining include protection of the bore against corrosion and ease of cleaning.

All other things being equal, it is generally considered that a Crome lined barrel is less accurate than a non-chrome lined barrel. The degree to which chrome lining degrades accuracy is debatable.

 

[GH41]

You posted in the semi-auto section so I will assume you are talking about AR barrels. I think you make your selection based on your intended use for the weapon. If you are after target grade accuracy pick a barrel made by a reputable builder and don't worry about what it's made of. If the gun is used for home defense and shooting dirt where 2MOA is acceptable buy a chrome or melonite lined barrel from a reputable builder and don't worry about what it's made of. I never understood the obsession over barrel life. If it takes $4-8000 worth of bullets to shoot out a $2-400 barrel what's the big deal??

 

[DT1]

You posted in the semi-auto section so I will assume you are talking about AR barrels. I think you make your selection based on your intended use for the weapon. If you are after target grade accuracy pick a barrel made by a reputable builder and don't worry about what it's made of. If the gun is used for home defense and shooting dirt where 2MOA is acceptable buy a chrome or melonite lined barrel from a reputable builder and don't worry about what it's made of. I never understood the obsession over barrel life. If it takes $4-8000 worth of bullets to shoot out a $2-400 barrel what's the big deal??

+1 Great Post! The vast majority of people will never even come close to shooting out a barrel so the type of steel is really a non-issue. You've nailed it as to whether on not to get a chrome lined barrel. Get a rifle or barrel from a reputable source for your purpose and worry about more important things like practicing good shooting fundamentals.

From what I've read, the military was wearing out barrels at around 800-1000 rounds due to the enormous heat generated from firing on full auto so they went to chrome lining to prolong barrel life.

 

[bustin]

So I'm confused. I can buy a barrel in 4142 chrome-moly, 416 stainless, 4140 chrome-moly, chrome vandamium, 410 stainless with chrome or melonite linings etc.

What advantages are offered by various steels regarding accuracy and barrel life?

Do you prefer a chrome lined or melonite lined barrels or plain old stainless?

Class is in session.

416 stainless is apx 28-32 rockwell, that is soft and will wear and fire crack/check sooner. Not all use the same grade stainless and some stainless barrels are known to be very soft, break in and wear out quicker. Shilen barrels are known to break in quickly.
410 is a little harder but not much. Button pullers are starting to use it again because it isn't as gummy and does not stick to the buttons.
Untreated 4140 or 4150 is around 30 rockwell also. Melonite treated 4140 or 4150 is 60-70 rockwell.
Chrome lined and Melonite barrels may last more than twice as long as stainless. Chrome will not be as accurate due to the difference in the hard coat.
Many assume if the barrel is stainless it is a match barrel but that isn't true. The material is not what makes it a match grade barrel.
Stainless or 4140 barrels chambered larger than a 5.56 Nato(.373) in diameter do not meet the required 2:1 safety factor in strength around the chamber. That is why the mil spec is 4150 11595E barrel steel.

 

[ddavis]

I recently shot out the chromoly 20" heavy barrel on my AR. I use it for carbine matches so it typically gets 30 rounds blasted through it in short order. It may have had 5000 rounds through it. I replaced it with a melonite/nitrided barrel, which I expect to last much longer. I had my 6.5 Creedmoor bolt action done in nitride for the same reason, as well as its other advantages. Nitride is very hard. In fact if you take a knife blade to it, it just dulls the knife and leaves no mark on the nitride. It is also corrosion resistance and leaves a nice flat black finish. I'm completely sold on the stuff. It didn't hurt the accuracy on my rifle but the jury is still out on that one. If you get a chance, pick up the latest issue of RECOIL magazine at Walmart. It has a good section on all the different coatings.

 

[ddavis]

I realized someone may call me out on this one so I'll correct myself. Unlike chrome/etc. Nitride is not a coating. It is a surface treatment. When you nitride a part, it keeps the same dimensions. I think the reason chrome can affect accuracy is because it doesn't always go on evenly but someone else may know more about that.

 

[BurnOut]

So, potential side discussion here, but since it was brought up... what is the general opinion of accuracy from Melonited barrels? I am in the process of getting geared up to re-barrel one of my guns, and am thinking about getting the barrel, running a few rounds through it to break it in/smooth the throat, cleaning the snot out of it, and sending it out to get the Melonite treatment. The goal (duh) would be to lengthen the accurate life of the barrel as much as feasible.

 

[bustin]

So, potential side discussion here, but since it was brought up... what is the general opinion of accuracy from Melonited barrels? I am in the process of getting geared up to re-barrel one of my guns, and am thinking about getting the barrel, running a few rounds through it to break it in/smooth the throat, cleaning the snot out of it, and sending it out to get the Melonite treatment. The goal (duh) would be to lengthen the accurate life of the barrel as much as feasible.

Do NOT drill the gas port before Melonite. After Melonite the threads of the barrel extension must be cleaned and the extension torqued again. It will not line up in the same spot so drill the gas port after re-torquing the barrel extension. If the threads aren't cleaned corrosion will build up in the threads, the liquid seeps in between the threads. The extension will loosen and the barrel will spin out of it. I've assembled 10s of thousands of Melonite treated barrels, it's the way it needs to be done pain in the ass or not.
Melonite does not effect accuracy, if the barrel was made correctly with the chamber concentric and stress relieved properly it will shoot. The Melonite is more corrosion resistant than ss, nickle or hard chrome, cuts down on copper fouling and makes the barrel last much longer along with increasing the burst strength.

 

[bustin]

I realized someone may call me out on this one so I'll correct myself. Unlike chrome/etc. Nitride is not a coating. It is a surface treatment. When you nitride a part, it keeps the same dimensions. I think the reason chrome can affect accuracy is because it doesn't always go on evenly but someone else may know more about that.

Correct, it's not a coating it's a heat treat, liquid salt bath.

 

[BurnOut]

bustin- I appreciate the info and tips.