11-01-2017, 02:10 AM
A problem I had with a bolt not head spacing might give you some food for thought. About a year ago I was putting together a precision upper with a stainless 18" .223 wylde hanson profile barrel from ballistic advantage. To complement the barrel, I got a NIB x (? I can't keep the proprietary Nickel boron coating names straight but you know what I mean) bcg from WMD. Both components were beautifully made, but I could not get the bolt to close on the "go" gauge. A standard phosphate bolt that came with a S&W M&P 15 did, however, head space with that barrel.
I sent the NIB bolt back to WMD to test and they said it head spaced fine on 5.56 barrels, which is all they had to test. WMD then sent the bolt to Clint Hanson at Ballistic Advantage, who had this to say: "It is measuring on the tight side with multiple BA barrels right off the floor. When I say tightÂ….1 out of 6 barrels took the go guage with this bolt. The other 5 would not close on the go." Ultimately, it seems the NIB coating increased the bolt's dimensions just enough that it would play with the wylde chamber.
Point being, since you went with a chrome bcg, it at least seems possible that you are having a similar problem as the result of dimensional changes caused by that coating. If you/your builder have access to another grendel bolt that would be an easy way to rule out the barrel as the problem if another bolt head spaces properly.
I sent the NIB bolt back to WMD to test and they said it head spaced fine on 5.56 barrels, which is all they had to test. WMD then sent the bolt to Clint Hanson at Ballistic Advantage, who had this to say: "It is measuring on the tight side with multiple BA barrels right off the floor. When I say tightÂ….1 out of 6 barrels took the go guage with this bolt. The other 5 would not close on the go." Ultimately, it seems the NIB coating increased the bolt's dimensions just enough that it would play with the wylde chamber.
Point being, since you went with a chrome bcg, it at least seems possible that you are having a similar problem as the result of dimensional changes caused by that coating. If you/your builder have access to another grendel bolt that would be an easy way to rule out the barrel as the problem if another bolt head spaces properly.