AR 15 Guru question.

[Shovelhead]

All else fails... Rub bacon on it.

All else fails I use non NiBx BCG in the 300BO

 

[Shrek926]

All else fails I use non NiBx BCG in the 300BO

Honestly it sounds like a deeper rooted issue. I helped Swamp Fox with his a few weeks ago, and zero problems with a NiBx. It truly sounds like a barrel extension issue.

 

[Shovelhead]

Honestly it sounds like a deeper rooted issue. I helped Swamp Fox with his a few weeks ago, and zero problems with a NiBx. It truly sounds like a barrel extension issue.

2nd barrel too.

OBTW just for giggles. I had the 1st barrel boxed and ready to ship back. I broke that bad boy out and guess what. Same-O Same-O
The NiBx Bolts do not rotate and lock in two different barrells with two different bolts with two different BCG. Non-NiBx no problemo......

 

[mtdawg169]

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.

I'm convinced that it's a tolerance stack issue. Barrel extension could be a little too shallow and the bolt lugs a little too long or fat = no worky. Basically you've got one part on the tight end of the spec and one part on the generous end of the spec, possibly even out of spec for the dimensions. Like I mentioned, I saw some bolts recently with the same issue, lugs were too long and wouldn't lock (in 2 different barrels from different manufacturers) . If you're milspec bolts work fine, I think you've found your answer. Following the "mod the cheapest part" mantra, if all else fails, sell the NiB bolts and install a known good milspec bolt.

 

[Shovelhead]

One of the things I like with CORE is their no BS warranty it will be in their court tomorrow