Stupid question about AR-15 barrel lining....

To chrome line a solution has to be stoppered up inside the bore and electric current added to precipitate chrome onto the surface to make it adhere to the metal. If the barrel was simply immersed in solution then all surfaces of the barrel would be chromed. To plate anything less than then entire chamber and bore would require inserting plugs to only treat that small area.

I don't know that they do that - the milspec is to chrome the entire bore and chamber, which would seem to be about the easiest thing to do rather than some tricky method of stoppering it partially and risking a loss of consumer confidence using a substandard method.

Chromed or not the barrels will last tens of thousands of rounds and the average shooter won't wear one out. It's not a method that increases accuracy, just improves corrosion resistance in a harsh environment.

I've had that upper. It was fine. Shot an inch at 100 yards. 100% reliable.
Then I got a rock river arms predator pursuit upper . It was fine. Shot an inch at 100 yards. 100% reliable.
Then I bought a palmetto state premium upper. It was fine. Shot an inch at 100 yards. 100% reliable.
Then I got my brothers palmetto freedom stainless upper. It was fine. Shot an inch at 100 yards. 100% reliable.
Notice a pattern? Personally that is a lot to pay for a pretty basic milspec, but quality, upper. In terms of barrels I would want I'd look for melonite/nitride, then stainless, then chrome lined, then parkerized, in that order.
You can pretty regularly get a good upper for under $400. Keep an eye on palmetto state armory or some other reputable site.

You can get either a chromed chamber or a chromed chamber and bore.

Tirod said:

To chrome line a solution has to be stoppered up inside the bore and electric current added to precipitate chrome onto the surface to make it adhere to the metal. If the barrel was simply immersed in solution then all surfaces of the barrel would be chromed. To plate anything less than then entire chamber and bore would require inserting plugs to only treat that small area.

I don't know that they do that - the milspec is to chrome the entire bore and chamber, which would seem to be about the easiest thing to do rather than some tricky method of stoppering it partially and risking a loss of consumer confidence using a substandard method.

Chromed or not the barrels will last tens of thousands of rounds and the average shooter won't wear one out. It's not a method that increases accuracy, just improves corrosion resistance in a harsh environment.

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Actually, hard chromium plating requires a current be passed through the solution from the anode to the work.

The process for chrome plating a bore is to immerse the entire barrel in the solution (no stoppering required) and put an cathode in the bore. Then you send a current through the work (+) through the solution, and to the cathode (-), as it passes through the solution to the cathode a chemical reaction takes place depositing chromium on the work.

All you have to do to keep from chrome plating the chamber is not send the electrical current through the chamber area, simply have a shorter anode.

The first M16 did not have both the chamber and bore chrome plated. The first ones were not plated at all, then they started to plate the chambers only to solve extraction problems caused by pitted chambers, then started to plate the entire inside surface.

These days, if a bore is plated, so is the chamber, no need for the plating shop to stock two different types of anodes.

You can get either a chromed chamber or a chromed chamber and bore.

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Where? I don't recall ever seeing just a hard chromed chamber but not bore for sale.

I'm remembering something about the reason for the original M16s having a hard chromed chamber but not bore was that the plating process wasn't set up for plating a .22 cal bore at the time. Once the platers got the process/tools figured out they have been plating the entire chamber and bore ever since.

BSW

They may not be a available as a new barrel. I've got an old colt upper with a chromed chamber though.

For that kind of money, you can buy a complete rifle kit at PSA and have money left over

It seems, in my experience, that the QPQ process is an improvement over traditional chrome-plating of chambers and/or bores...more uniform, hard, and dependable for tens of thousands of rounds.

That is, better accuracy from the start and better accuracy for longer round counts because the process is so predictable in tolerances, and, therefore, highly dependable over time.

Technology marches on...and that is the most accurate answer to the OP's question.

Melonite seems to be a better treatment than chrome, it actually changes the structure of the steel, makes it very hard and durable. Both of my AR's have the melonite coating.

Funny how the first S&W Sport was perceived as 'cheap' and of dubious quality before anyone had a chance to test one.

A few years later and the nitrided Thompson Center made barrel is considered the thing to have.

The only rifles with chromed chambers, but not bores, are some of the classic Colts floating around Gunbroker. I can't think of a single modern example.

Chrome lined barrels, while not having the capability of being as accurate as a high dollar match grade barrel, has every ability to be as accurate as an entry or mid-level stainless/melonited barrel. If you are looking at that Spikes, and it is a good upper even if I don't care for carbine gas, I'd recommend this one instead. It is cheaper, comes with MOE hand guards, and has free shipping. http://www.aimsurplus.com/product.aspx?item=XSTU5025MOE

Funny how the first S&W Sport was perceived as 'cheap' and of dubious quality before anyone had a chance to test one.

A few years later and the nitrided Thompson Center made barrel is considered the thing to have.

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There always has been a misunderstanding on the WWW about the difference between budget and beginner. I doubt it will ever change.

No, that is essentially par for the course when it comes to barrel extensions.

The best way to check reliability is to just get out and shoot the thing!

it's a good thing you didn't look down the barrel and see a "burr" where they drilled the hole for the gas block.

melonite-nitride is the way to go now. Should last almost indifinitely.

My next build will be a melonite treated barrel.

OP, look at MAS Defense prebuilt uppers and BCM uppers. Then just snap it on the lower of your choice.

To be honest, I wouldn't sweat the chrome whatever. Unless this is a hardcore defensive carbine. Then you should be more picky.