No koolaid here, just 15 years of satisfaction with hard chromed AR barrels. I understand that melonite is working for you and that is great to hear. Your feedback is appreciated and I have learned new things about melonite from your helpful posts.

My early XD40 slide will rust if you look at it the wrong way. It may be pre-melonite though. That is a distant memory, but it seems like the early guns were finished different than the later production units. Is that correct?

It may just be that I am suspicious by nature when it comes to things like this. Let me explain. Hard chrome is a separate process. Wouldn't melonite treatment be done to the bore and exterior of a barrel at the same time? If so, that eliminated a process step (and increased profit margins?) in manufacture. I can't help but wonder if that is really the motivation behind deviating from the milspec.

If melonite proves itself over the next few years as being better than chrome, I'll eventually change. To prove that in my mind, the US Military will need to adopt it as the new standard.

Until then, I'll personally stick with hard chrome because it has worked for me over the tens of thousands of rounds of 556 downrange in the past years. It has also worked for our military for the past 50 years.

Back to the OP, I wouldn't worry to much about a small amount of copper fouling in an assault rifle barrel. If it gets heavy, there are product readily available that will get it under control.

Happy shooting.