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300 BLK Barrels: Nitride Heat Treatment vs. Chrome Lining

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We’re often asked, which barrel treatment is better? Chrome lining or Nitride? The short and sweet answer doesn’t exist – they each have their benefits and drawbacks. Remember, 300 BLK is a multi-purpose cartridge inside a versatile rifle (or pistol) platform. Picking the right 300 Blackout barrel will depend on what you want to use your gun for.

Chrome lining, what is it?

Chrome lining is exactly what it sounds like: A physical lining of chromium that’s added to the inside of the rifle bore. Chrome lining is applied through an electrochemical process. First, the barrel in question is rifled – usually a bit bigger than the intended final dimensions. It’s then submerged in a liquid solution that prepares it for electric current.

An anode – a positively charged electrode that allows electrons to flow through the barrel – is placed inside the bore. Once electrically charged, the barrel attracts the chrome lining material and it is bonded with the bore. This addition of material brings the bore’s final dimensions into specification. Usually, a polishing treatment is done to ensure smoothness.

Why chrome lining is awesome

Chrome lining is just a few thousandths of an inch thick, but it provides excellent corrosion and abrasion resistance. It also makes cleaning your rifle’s bore quicker and easier – chrome lining is hard and non-porous, so it absorbs fewer contaminants.

More importantly, chrome lining increases barrel life and reduces rifling wear. The myth is that chrome lining extends barrel life by a fixed number of rounds – many believe if your barrel would last 8,000 rounds, chrome lining might extend that number to 10,000 or 11,000 rounds. This is false.

Chrome lining protects your AR 15’s rifling from excessive heat. See, 300 BLK is a heavy round and supersonic rounds move pretty fast. This generates a lot of heat inside the bore. Heat degrades metal and makes it soft, killing the sharpness of your rifling.

Chrome lining vastly extends the limits to which your barrel can get hot before degrading – that’s why the U.S. Military started using chrome lining: Not to extend barrel life by number of rounds fired, but by the mere fact that soldiers like to shoot a lot of rounds very quickly in a firefight.

Chrome lining doesn’t kill accuracy

Contrary to popular belief, chrome lining will not turn your precision 300 BLK gun into an old AK 47 that got dug up and rebuilt as a parts kit sourced shadily from one of the “stan” countries. Chrome lining, when applied properly, will still produce a 300 BLK barrel that’s capable of sub-MOA accuracy. Can it degrade accuracy? Yes, because it’s adding material to the rifling in a relatively less-precise manner – but the amount of accuracy lost will be negligible for most shooters.

Nitride, what is it?

Nitride is not a material-adding treatment like chrome lining. Instead, nitride modifies the existing barrel steel in your 300 BLK by mating with the metal itself. This is accomplished through submitting the barrel to a plasma or liquid salt-bath treatment filled with nitrocarburization processes.  

The addition of nitride dramatically hardens the steel at the surface (and a few thousands of an inch below the surface) of your barrel. It, too, greatly increases corrosion and abrasion resistance.

A small bonus is that the treatment provides the same benefit to the exterior of your barrel, so there is no need for phosphate coating to be applied like a chrome lined barrel needs. Instead, a black oxide finish is applied that can be gloss or matte, though this is more for aesthetic purposes.

Why nitride treatments are awesome

Nitride treatments don’t physically alter the shape or profile of a rifle’s bore. If a rifle blank was cut precisely enough to afford sub-MOA accuracy, that accuracy will only improve. It will not degrade like chrome lining might cause, because no material is being added to the bore, modifying the shape of the finished rifling.

Instead, the nitride treatment is only hardening the rifling, improving consistency and reducing deposit build-up in the bore. This is why nitride treatments can actually improve accuracy.

Nitride is less expensive

Nitride treatments are significantly less expensive than chrome lining. The result is a more affordable 300 BLK barrel or built 300 BLK upper that’s extremely accurate, long-lasting and rugged.

Which is better?

To keep it simple, chrome lining will benefit you in rapid-fire situations. If you shoot plenty of supersonic 300 BLK rounds relatively quickly and if you enjoy spending little time cleaning your rifle’s bore, chrome lining is the way to go.

Nitride treatments will still benefit in rapid-fire situations, just to a lesser extent. How much so? The difference, truthfully, is negligible. Unless you plan to mag dump 100+ rounds of 300 BLK on a hot summer’s day over and over, you’ll be fine with either treatment. Nitride will also generally provide slightly better accuracy.

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