MR556/HK416 HKParts.net 10.4in barrel conversion kit

HKParts 10.4 barrel

A little while back I came into a couple of cheap MR556 uppers where the barrels had been trashed.  I expected getting a replacement HK barrel wouldn’t be too bad.  That was a mistake.

As I went to shop around for barrels, I found Brownells listed them.  Right now I am unable to find it on their website, but it had a list price of about $800 and was constantly out of stock.

I wasn’t too happy with that price, and even so, couldn’t even get one since Brownells was out of stock.  HK did not respond to my attempts to purchase a barrel from them.

Then I found HKParts.net 10.4 inch aftermarket barrel.  Still very expensive at $589.95 and $49.99 S&H, it is a little cheaper than the unavailable stock MR556 barrel.

Much to my dismay, I found my barrel kit came in pre-rusted for me.  My pictures don’t show it well, but there was rust on the flash hider, crush washer, barrel, gas block, gas block roll pins, and barrel extension.

2016-05-04 18.33.48

2016-05-04 18.33.43

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2016-05-04 18.34.18

Not very impressive for the most expensive barrel I own.  On the plus side, the barrel nut and barrel wrench weren’t rusted.  That counts for something, right?

Anyways, the installation went easily.

Now here is the part I don’t really feel like admitting.

Over two range sessions, using 3 different types of ammo, and 3 different optics, I was only getting 4 inch groups at 25 yards.  I was really not happy.

Well turned out it was user error.  See the HK hand guard has a tang to fit into a notch in the upper receiver.  Since I had just installed this barrel, I had left the hand guard loose so I could quickly remove it.  On each of the 3 optics I used (Aimpoint M4, NF2.5-10X, MK6 3-18), I had the mount run over this tang, and pressure on the hand guards was putting pressure on my scope mounts, throwing off the groups.

Once I finally realized what I had done, I moved the optics back a notch and finally had dime sized groups at 25 yards.  I haven’t any real accuracy testing past that, but it is more reasonable than a 4 inch group.

Ultimately cost can become a major issue with anything HK.  The cost and availability of replacement parts is ridiculous.

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