Shooting Range in Vegas sharing info on what works and what doesn't...

[nova3930]

For those that don't know, the MR556 has a melonited barrel (not Chrome Lined like the 416). From talking to several BIG AR manufacturers, they reported that melonited barrels failed accuracy reqs well under 5,000rds when shot on FA. Apparently on SA, it takes a bit longer to fail (10k). Interesting....

C4

I had seen some stuff in the academic literature about nitrocarburizing breaking down at temperature/pressure extremes but nothing explained in detail. This is the first real world evidence of that i've seen. Makes sense when you think about the typical applications being gears, cams and external surface treatments, all things that don't see 3000+ deg and 40+ksi

[KalashniKEV]

That was not surprising regarding the melonite... this was, a little:

USGI mags have outlasted all of the other brands. We use UGSI (Brownell’s with tan follower) and on a mag for mag basis, they have outlasted Pmags and a few of the other mags that we get from mfg’s with new weapons. We don’t have to worry about various generations with different weapons like the MR556, SCAR, F2000, Tavor or a couple of others that use AR15/M4 magazines.

[scottryan]

Nothing is this thread is suprising to anyone who has been paying attention and is actually using/building guns.

Melonite is just a way for a manufaturer to claim their barrels have some type of surface treatment while the melonite really does nothing except generate profits on hobby/consumer grade firearms.

[scottryan]

That was not surprising regarding the melonite... this was, a little:

Not suprised at all.

[PatrioticDisorder]

Yes. HK USA confirmed they are coated.


C4

Isn't melonite a treatment and not a coating? And when did HK USA start having the Mr556 barrels melonite? There are companies and people who own MR556 uppers and rifles that have been paying to have their barrel nitrided (see link).

http://www.investmentgradefirearms.com/mr-556/

While i cannot find the link, on HKPro forum others have previously addressed the keyholing at 10k round issue and if memory serves me others have had the same problem due to copper fouling that was fixed after a thorough cleaning of the barrel (due to being non chrome lined or melonited).

[KalashniKEV]

Not suprised at all.

I said "a little" because it contradicts what I had been told, but not my own experience.

[C4IGrant]

I had seen some stuff in the academic literature about nitrocarburizing breaking down at temperature/pressure extremes but nothing explained in detail. This is the first real world evidence of that i've seen. Makes sense when you think about the typical applications being gears, cams and external surface treatments, all things that don't see 3000+ deg and 40+ksi

Right. With talking with some of these companies, it is pretty well assumed that the pressure and heat is what kills the barrels. Since that MR556 was shot SA, it just took longer.

On the flip side, quality CL barrels don't key hole till 20k or longer.



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[Cane55]

Yes. HK USA confirmed they are coated.


C4

Thanks for the info, I was unaware of that.

[C4IGrant]

Isn't melonite a treatment and not a coating? And when did HK USA start having the Mr556 barrels melonite? There are companies and people who own MR556 uppers and rifles that have been paying to have their barrel nitrided (see link).

http://www.investmentgradefirearms.com/mr-556/

While i cannot find the link, on HKPro forum others have previously addressed the keyholing at 10k round issue and if memory serves me others have had the same problem due to copper fouling that was fixed after a thorough cleaning of the barrel (due to being non chrome lined or melonited).

Correct. It is a treatment.

The inside of the barrel is melonited and not the outside. So that is what they are paying for.





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[C4IGrant]

Isn't melonite a treatment and not a coating? And when did HK USA start having the Mr556 barrels melonite? There are companies and people who own MR556 uppers and rifles that have been paying to have their barrel nitrided (see link).

http://www.investmentgradefirearms.com/mr-556/

While i cannot find the link, on HKPro forum others have previously addressed the keyholing at 10k round issue and if memory serves me others have had the same problem due to copper fouling that was fixed after a thorough cleaning of the barrel (due to being non chrome lined or melonited).

I guess copper fouling could do it, you would have had to completely ignore cleaning your barrel for YEARS. To date in all my years, I have never seen this. Copper fouling wasn't the case for the Vegas range. They clean and lube their guns regularly.



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