Toolcraft initial 6.5 Grendel bolts were 2.80 long from the rear of the bolt tail to the face of the bolt. The bolt face depth of the Toolcraft 6.5 Grendel bolt should be .136. Alexander Arms chose to use a bolt length of 2.810 to account for the deeper bolt face and the ability to use milspec firing pins. Ive measured all of my firing pins and bolts and was amazed at the various lengths of bolts and firing pins whether 6.5 Grendel or 5.56/223. With a 2.800 length bolt you need a .01 shorter firing pin.
The AR-15 has a specification for firing pin protrusion, deviate from this spec and you can have failure to fire or pierced primers. The minimum firing pin protrusion is .028 and the maximum is .036. Brownells sells a firing pin protrusion gauge. In essence there is a tolerance of .008 between the length of the bolt and firing pin length that need to be in spec. It is possible to get a bolt that is to long or short and I found significant variation in firing pin overall lengths.
I have not found an official document for the exact milspec for firing pin overall length but I believe it is 3.279 plus or minus tolerance. If you measure bolt and it is 2.810 + FP length 3.279 = 6.089. Your two measurements together need to be within .008 of 6.089. As example if you have a shorter 2.80 Toolcraft bolt your firing pin needs to be .01 shorter or approximately 3.269. Adding 2.800+3.269=6.069. Your bolt length plus firing pin length needs to be within .008 of 6.069.
To avoid confusion it appears recent Toolcraft bolts are now shipping with 2.810 length bolts and milspec length firing pins. In measuring my 6.5 Grendel bolts I found where my bolts were within .004 of the stated 2.810 length. Interestingly the longer bolts or shorter bolts were paired with FPs to acheive the proper FP protrusion. It appears that during assembly the the assembler has a batch of bolts and firing pins and checks to see if the selected bolt/firing pin are within spec for firing pin protrusion. If the bolt/FP is out of spec another firing pin is used to get the FP protrusion within specification.
For these reasons I dont recommend swapping firing pins without first measuring the bolt and firing pin length. I found these same variations in manufacturing tolerance when comparing my 5.56/223 bolts and firing pins. In every case the bolt and firing pin were within the .008 spec for firing pin protrusion. It is not uncommon to find .004 variation in bolt or firing pin lengths when comparing numerous AR-15s.
The AR-15 has a specification for firing pin protrusion, deviate from this spec and you can have failure to fire or pierced primers. The minimum firing pin protrusion is .028 and the maximum is .036. Brownells sells a firing pin protrusion gauge. In essence there is a tolerance of .008 between the length of the bolt and firing pin length that need to be in spec. It is possible to get a bolt that is to long or short and I found significant variation in firing pin overall lengths.
I have not found an official document for the exact milspec for firing pin overall length but I believe it is 3.279 plus or minus tolerance. If you measure bolt and it is 2.810 + FP length 3.279 = 6.089. Your two measurements together need to be within .008 of 6.089. As example if you have a shorter 2.80 Toolcraft bolt your firing pin needs to be .01 shorter or approximately 3.269. Adding 2.800+3.269=6.069. Your bolt length plus firing pin length needs to be within .008 of 6.069.
To avoid confusion it appears recent Toolcraft bolts are now shipping with 2.810 length bolts and milspec length firing pins. In measuring my 6.5 Grendel bolts I found where my bolts were within .004 of the stated 2.810 length. Interestingly the longer bolts or shorter bolts were paired with FPs to acheive the proper FP protrusion. It appears that during assembly the the assembler has a batch of bolts and firing pins and checks to see if the selected bolt/firing pin are within spec for firing pin protrusion. If the bolt/FP is out of spec another firing pin is used to get the FP protrusion within specification.
For these reasons I dont recommend swapping firing pins without first measuring the bolt and firing pin length. I found these same variations in manufacturing tolerance when comparing my 5.56/223 bolts and firing pins. In every case the bolt and firing pin were within the .008 spec for firing pin protrusion. It is not uncommon to find .004 variation in bolt or firing pin lengths when comparing numerous AR-15s.