AR 15 Guru question.

[b.a.customkydex]

I'm just up 9 in Dawsonville, depending on where you are in Cumming I could come look at it if you want.

 

[Shovelhead]

Does the head of the NiBx bolt fit all the way into the barrel extension when neither are mounted in the receiver?

Yes.. If the barrel is inserted just a hand tightened barrel nut it's a NO-GO. outside the upper seems functional.

 

[mtdawg169]

Could it be the M4 cuts look at the BO barrel on left the 223 on the right???

Doubtful. If you have a set of calipers, measure the lug lengths on each bolt and post up the results. A buddy of mine ran into this recently with a couple of RCA bolts. Not sure where they source their bolts from, but there is some bad product on the market. I also ran into this a few months ago with an NiB bolt. It's lugs were a couple thousandths longer than a BCM bolt.

 

[Shovelhead]

So worst case scenerio you can still use the non NiBx BCG with the 300 BLK and the NiBx BCG in the .223 and still have two complete functional uppers. Not all bad.

Yep the 300 BO Barrel (a second one from Seekins) doesnt like Nickel Boron .......go figure?

 

[mtdawg169]

OK it's two BCG's so I'suspecking the 300BO which
by the way is the second one I recieved because we thought the 1st one was the culprit.

So this is the second BO barrel that the NiB bolts would not work in?

 

[b.a.customkydex]

Yes.. If the barrel is inserted just a hand tightened barrel nut it's a NO-GO. outside the upper seems functional.

If it works outside the upper.....actually put the upper together....what MAY be happening is the barrel is sliding forward JUST enough to keep from locking up.

 

[Shovelhead]

It's BOTH of the NiBx bolts. If I put the no Nickel in a Nickel BCG it works fine any barrel any upper.
If I put the Nickeled Bolts in a Non Nickel BCG it does not function.

There is something with the bolts. Two separate sources too.

 

[Zeake]

mic the lugs on the bolts . . . . . .

 

[Shovelhead]

Dont have a micrometer (IT Geek not a tool & die maker) I have digit calipers and cant see a difference. It is only the combination of bolts that are NiBx treated in this Seekins 300 Barrel. All uppers, all BCG, all bolts work fine with the 223/5.56 barrel

I have another NiBx BCG from ICE arms coming sometime this week it will be interesting to see if a 3rd one fails to lock up.

 

[Shrek926]

All else fails... Rub bacon on it.