[Spartan5]

So not to sure why but after looking at it I do like the look of an extended castle nut not sure why but its a good look but a little birdie told me that the HK extended castle nut has a proprietary thread pitch? So if Im hearing that right it wouldnt be able to use regular buffer tube/ receiver extensions? Does the extended castle nut impact LOP? or would I still need a receiver extension? Thank ahead of time

 

[JNAP94]

So not to sure why but after looking at it I do like the look of an extended castle nut not sure why but its a good look but a little birdie told me that the HK extended castle nut has a proprietary thread pitch? So if Im hearing that right it wouldnt be able to use regular buffer tube/ receiver extensions? Does the extended castle nut impact LOP? or would I still need a receiver extension? Thank ahead of time

It's not proprietary it just doesn't fit properly on a Commercial Buffer tube, but (as stated below now) does on the Mil Spec Tube which is what is present on the HK 416 A5. Ask UMP45entry.. He mentioned to possibly having to have threads milled off inside castle nut to work on (what I now know was) a Commercial buffer tube about halfway across inside of Nut..

It had been a long time since our discussion and I could not remember how he ended up resolving the issue..

 

[UMP45 ENTRY]

I have a couple of these new A5 castle nuts on my rifles, I love them. They do not fit on the commercial buffer tubes but fit right on the mil-spec tubes as that's what the A5 uses.

 

[JNAP94]

I have a couple of these new A5 castle nuts on my rifles, I love them. They do not fit on the commercial buffer tubes but fit right on the mil-spec tubes as that's what the A5 uses.

Been awhile I couldn't remember what you had done!!

 

[UMP45 ENTRY]

Been awhile I couldn't remember what you had done!!

Yeah, when I first got them I tried to install it on a commercial tube and didn't have a mil-spec tube floating around. I did eventually get it to work with the commercial tube by boring out the rear of the nut to fit over the commercial threads and tube. Just grab a mil-spec tube and you're good to go.

 

[Javier]

where is the best and cheapest place to buy this extended nut?

 

[UMP45 ENTRY]

where is the best and cheapest place to buy this extended nut?

Only place I've ever seen them for sale so far is German GunWorks

Currently out of stock:

http://www.germangunworks.com/heckler-koch-hk416-mr556-extended-buffer-tube-extens-p-3358.html

 

[RegularGuy461969]

Am I crazy, don't the MR556s come with mil spec tubes?


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[Oicani]

I'm pretty sure it's a commercial tube.

 

[RegularGuy461969]

Confirmed, you are correct.


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[Oicani]

I've always found it rather strange why HK wouldn't go with a commercial tube, but than again we don't want to confuse it with the HK416.

 

[DontTreadOnMe]

Mine definitely has a Mil-Spec tube.

 

[RegularGuy461969]

This is s great thread. I think it needs to go into the library or become a sticky.

Mods, oh Mods where are you Mods???


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[Oicani]

Or added to the FAQ thread that PB started.

 

[RegularGuy461969]

So I am bringing this back to life because I ordered a milspac HK buffer tube and received it.

These A5 extended castle nuts fit perfect on it. It does appear that the back half of the castle nut threads are shorter than the front half. It sails right over the unthreaded buffer tube.

The funny thing is, it's identical to the MR and CR556 lower buffer tubes that I have on all my 416 upper/556 lower rifles.

Now I've got to send my lowers to James @Marine0303 to have them installed.