12-15-2023, 12:23 AM
VASCAR2 Wrote:A couple 6.5 Grendel manufactured bolts/BCG use a shorter firing pin. The reason is because Bill Alexander used .136 bolt face depth. A standard AR-15 5.56/223 bolt face depth is .125 and the bolt length is 2.800. Bill A. lengthened the 6.5 Grendel bolt to 2.8100 to permit the use of the same length firing pins as AR-15s in 5.56/223.
When Odin Works released their 6.5 Grendel BCG they used .136 bolt face depth. Odin kept the same bolt length at 2.800. Odin Works barrels started getting reports of pierced primers which was traced to excessive firing pin protrusion. The spec for firing pin protrusion on an AR-15 is minimum .028 to maximum .036. It was discovered Brownells BCG use the .280 length bolt but use a shorter firing pin. Odin last reported uses a shorter firing pin. Early Toolcraft 6.5 Grendel bolts were reported to be 2.800 length but Toolcraft supposedly switched to 2.8100 length bolts.
The AR-15 spec for AR-15 firing pin length is 3.280 with a tolerance of -.009. I wouldnt run a firing pin longer than 3.269 long with a 2.800 length bolt. There could be other 6.5 Grendel bolts manufactured with a length of 2.800. I would not mix up my firing pins in an AR-15 as you can get into tolerance stacking. You cant assume any AR-15 firing pin will automatically fit every 6.5 Grendel AR-15. There is normally a tolerance of + or - .002 or more in AR-15 parts.
If I needed to shorten an AR-15 firing pin I would buy a Stainless Steel firing pin over a chrome lined CMV steel firing pin.
Very neat thanks.