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I'm not an Operator, not a LEO nor do I run N' gun, just an avid shooter.

Now that the barrels have their hole, it’s time to add in the rifling. There are two main methods to putting the grooves on the inside of a barrel: button rifling and cold hammer forging. Button rifling involves sending a button broach tool down the length of the barrel using hydraulic pressure that cuts and form the rifling into the barrel. Cold hammer forging involves bashing the barrel from all sides with hammers and forcing them to contact onto a tool, a mandrel, inside the barrel which has the mirror image of the desired rifling on it. Hammer forging has been proven to be the most accurate method of barrel production, providing a longer useful barrel life and greater accuracy. However, while cold hammer forging takes about 90 seconds per barrel (plus a longer setup time), button rifling is a much quicker process at about 30 seconds per barrel.

One of the more interesting things about the FNM barrel shop is that while button rifling is cheaper, everything that they make is cold hammer forged by default. The only reason they even have a button rifling process in the factory is that some U.S. military TDPs or “Technical Data Packages,” which outline product specifications, require the process to be used. But given the choice, J-P seems to prefer producing cold hammer forged barrels instead.

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If they were not chrome lined you  might get some kind extended life from the hammer forged barrel. Big might as far as I am concerned. You arent going to wear out a chrome barrel so i would save a few bucks up front. In the unlikely event you wear one out you will have probably spent 10 times as much as you spent on the barrel in ammunition.