OFCC University 103 (Internal Coatings)

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Re: OFCC University 103 (Internal Coatings)

Postby Mr. Glock » Sun Jan 11, 2009 1:04 pm

Any production standard pistol barrel is going to have wider tolerances than, say, a match barrel. The question is...do you need that extra little bit of accuracy in a CC piece, or would you rather have the reliablity built into the gun originally? It's not always an either/or...but if you start taking tolerances out, then you increase the likely hood that the gun will be more finicky.

If you shoot targets or the "game" sports, then you don't really have to worry about jams etc. In the real world, you should lean toward reliability IMHO.

With Glock, the type of rifling used is very good for jacketed bullets (both in more retained pressure behind the bullet in the barrel and for cleaning) but builds up lead faster than a standard rifling pattern found on, say, an XD. So, people who shoot alot of lead reloads might want an extra barrel. It's not that Glocks can not shoot lead, they are just optimized for jacketed.

But you should clean your barrel between shooting lead and jacketed in any gun....they work against each other in the barrel (the residue).
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Re: OFCC University 103 (Internal Coatings)

Postby CCIman » Tue Jan 05, 2010 10:15 pm

"Nitrided' barrels:

Does anyone know if the Glock barrels are nitrided? Any others?

One AR manufacturer (CMMG) uses a "nitrided" chromoly barrel, which they call their WASP finish. Are there any downsides in the process of "nitriding" the barrel (vs. chrome lining a barrel) that makes this a bad idea? Assuming that all is done correctly, I am currently thinking that a nitrided barrel is more wear/corrosion resistant than chrome lined. If I am correct on this, why not more of this in the rifle market?

Are there aftermarket metal treating services for barrels and slides that will not ruin the original, and worthwhile? (There are several firms in Cincinnati that offer metal treating services as those dicussed in these forums).
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Re: OFCC University 103 (Internal Coatings)

Postby willbird » Tue Jan 05, 2010 11:42 pm

I guess I never noticed the question on accuracy.

Yes the premium barrels are worth the extra money.

Maybe not for shooting Deer in PA where a 100 yard shot is rare. But for connecting at longer ranges a MOA accurate rifle is a serious handicap.

Consider that a MOA accurate rifle will only group in the neighborhood of 4" at 400 yards, but the top notch barrel may group 1" or a little more. When you factor in wind, and errors in distance estimation that 3" group size reduction may be a big help.

It is actually hard to buy a "bad" aftermarket barrel, most of them are far better than a factory barrel, the cheapest like Adams and Bennet and Shaw may only be equal to a factory barrel.

Typically only people who shoot a LOT will ever wear out a rifle barrel.........thus they are the ones who will benefit from a Shilen, Hart, PacNor, or Lila barrel.

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Re: OFCC University 103 (Internal Coatings)

Postby Morne » Tue Jan 05, 2010 11:44 pm

CCIman wrote:"Nitrided' barrels:

Does anyone know if the Glock barrels are nitrided? Any others?

One AR manufacturer (CMMG) uses a "nitrided" chromoly barrel, which they call their WASP finish. Are there any downsides in the process of "nitriding" the barrel (vs. chrome lining a barrel) that makes this a bad idea? Assuming that all is done correctly, I am currently thinking that a nitrided barrel is more wear/corrosion resistant than chrome lined. If I am correct on this, why not more of this in the rifle market?

What you are thinking of is actually "carbonitriding" or "nitrocarburizing". One is via gas medium and the other via cyanide salt bath but they produce essentially the same coating. The "Tenifer", "WASP" and other coatings are just fancy tradenames for these very common surface modification heat treatments.

"Nitriding" is a process that imparts ONLY Nitrogen into the surface of the steel, typically with cracked ammonia gas. "Tenifer" and "WASP" do more than that, they also add Carbon.

If you are looking at surface hardening a low-alloy steel then "nitrocarburizing" is just fine. Just remember that underneath that layer of hardness you still have soft steel (one of the alledged reasons for Glock kabooms, by the way). This is also a CHEAPER process than straight nitriding, since it adds two interstitial hardening atoms at once. That's why it is so popular.

If you are looking at surface hardening stainless steel then STAY AWAY from any and all "nitrocarburizing". Why? Because the intruding Carbon will bind with the free Chromium (which you need 12% minimum of to be considered stainless) and bind it up as Chromium Carbides. This is the EXACT same phenomenon as "weld sensitization" sometimes seen in stainless steels (for you welders, this is the reason the "L" grades like 316L were invented, less Carbon meant less weld sensitization). The result will be a loss of the "stainless" quality of the steel. If you are EVER going to "nitrocarburize" then you should NEVER use stainless. PERIOD.

None of these surface modification heat treatments improves the overall corrosion resistance of the steel. I know folks claim that they do - but they don't. You can show a resistance to forming rust bubbles but that's only because the matrix is harder. After a certain amount of time, though, corrosion will still claim its victim. In fact, with stainless steels that have been "nitrocarburized" they will actually corrode MUCH MORE QUICKLY than if they had been just Nitrided (or left alone entirely).

Chrome acts PARTIALLY as a barrier coating so you do get some corrosion resistance boost. It ain't perfect, either, but it is pretty darn good and has the advantage of being time-tested.

As to the "wear resistance" question - this is not nearly the common boogeyman that it gets played up as. In rifle barrels there is simply more erosion due to the passage/redirecting of hot gasses at the throat (and muzzle) than damage due to "wear" from bullet rubbing. Even if there were NO WEAR AT ALL from bullet passage you would still need to replace most barrels at the same time due to the throat and muzzle erosion issues. Hardness is not a factor in these places at all - steel chemistry and manufacturing process is a factor.

If it were ME and I wanted the best lasting barrel for all time I'd go with a vacuum-arc-remelted (VAR) grade of 15-5 PH stainless in the H1000 heat treat condition that was then GAS NITRIDED. Why? The VAR grade gives you finer grain size which should help with intergranular attack (IGA). The H1000 condition gives you a temper that can survive being gas nitrided at 975 F without softening. Of course, you'll never find anyone making a barrel like this (note that 17-4 is not made to VAR grade to my knowledge, it is strictly an ESR grade of steel).

Chrome is just fine. I encourage ANYONE who can buy a chromed barrel to do so. Playing around with fancy tradename coatings might help if you are a journalist with one of the various gun periodicals but otherwise it is just silly.

As to the aftermarket stuff you mention - provide a link and I'll provide an opinion.
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Re: OFCC University 103 (Internal Coatings)

Postby willbird » Wed Jan 06, 2010 12:04 am

Well there is a trade off in barrel materials. Softer materials cut or button easier or better, so a barrel made from them may be more accurate to begin with.

Savage rifle barrels are quite soft, this is part of why they are often quite accurate, BUT they wear faster. A remington hammer forged barrel may not be quite as accurate on average, but it will last a lot longer.

Some of what may be the "best" materials just do not lend themselves to the machining process's we have at present to make a rifle barrel.

According to one barrel maker turned brass bullets used in some calibers by long range shooters actually wear a bore faster than the powder erodes it, so a chrome moly barrel will give a longer accurate life for that use than a 416r stainless barrel will.

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Re: OFCC University 103 (Internal Coatings)

Postby Mr. Glock » Wed Jan 06, 2010 11:53 am

What is this?

http://www.realtree.com/products/gearGu ... php?ID=522

Sorry, the root URL does not work right now, you may have seen this in a few gun mags. Smooths the barrel, but you can't clean with a wire brush....ceramic?
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