I think your making this more difficult than it needs to be. I suggest you look at the BHW barrel and see if it is marked type I (1) or Type II (2). If the Black Whole Weaponry barrel is marked type I it is chambered to use a 7.62x39 bolt with a bolt face depth of .125 inches. If the barrel is marked type II the barrel is chambered to use a 6.5 Grendel bolt with .136 inch deep bolt face. If the chamber and bolt are in spec within .001 + or- then you should be gtg. The chamber gauges should verify the barrel and bolt are compatible.
The bolts are heat treated and I would not modify a bolt or chamber. If I had a stainless steel barrel with a short chamber I might use a finish reamer if it could not be returned to the manufacturer.
If your unable to determine which bolt the barrel is chambered to use call BHW/Columbia River Arms for assistance. If the BHW barrel uses a Type II 6.5 Grendel bolt get a Maxim left hand 6.5 Grendel bolt. Don’t try to deepen a 7.62x39 bolt, it is cheaper and safer to buy the appropriate bolt.
The reason Bill Alexander chose the .136 bolt face depth was to give more room for the extractor just like Colt had done with their 7.62x39 AR-15. A standard 5.56/223 bolt uses a .125 bolt face delth and most x39 manufacturers use a .125 inch bolt face depth. If you deepen a x39 .125 inch bolt the tail to lug face will be to short and you will need to shorten the firing pin. Most 6.5 Grendel bolts measure 2.810 inches in length from the tail to the face of the bolt lugs. (+or- .001). Standard .125 bolt face depth bolts measure 2.800 inches in length from the tail to the bolt face. Bill A. lengthened the tail .01 inches to account for the deeper bolt face depth and permit the usage of mil spec length firing pins. The spec for firing pin protrusion on the AR-15 is a minimum of .028 inch to maximum .036 inch. Brownell?s sell a firing pin protrusion gauge.
http://www.maximfirearms.com/online-stor...left-hand/
https://www.brownells.com/gunsmith-tools...26477.aspx
The bolts are heat treated and I would not modify a bolt or chamber. If I had a stainless steel barrel with a short chamber I might use a finish reamer if it could not be returned to the manufacturer.
If your unable to determine which bolt the barrel is chambered to use call BHW/Columbia River Arms for assistance. If the BHW barrel uses a Type II 6.5 Grendel bolt get a Maxim left hand 6.5 Grendel bolt. Don’t try to deepen a 7.62x39 bolt, it is cheaper and safer to buy the appropriate bolt.
The reason Bill Alexander chose the .136 bolt face depth was to give more room for the extractor just like Colt had done with their 7.62x39 AR-15. A standard 5.56/223 bolt uses a .125 bolt face delth and most x39 manufacturers use a .125 inch bolt face depth. If you deepen a x39 .125 inch bolt the tail to lug face will be to short and you will need to shorten the firing pin. Most 6.5 Grendel bolts measure 2.810 inches in length from the tail to the face of the bolt lugs. (+or- .001). Standard .125 bolt face depth bolts measure 2.800 inches in length from the tail to the bolt face. Bill A. lengthened the tail .01 inches to account for the deeper bolt face depth and permit the usage of mil spec length firing pins. The spec for firing pin protrusion on the AR-15 is a minimum of .028 inch to maximum .036 inch. Brownell?s sell a firing pin protrusion gauge.
http://www.maximfirearms.com/online-stor...left-hand/
https://www.brownells.com/gunsmith-tools...26477.aspx