There is a spec for the proper firing pin protrusion min. 028 to maximum .036 from the breach face. Brownells actually sells a gauge to quickly check to see if the bolt/FP are within spec.
https://www.brownells.com/gunsmith-tools...26477.aspx
This issue has come up before where tolerance stacking causes light strikes. Some times the bolt overall length is greater than 2.81 and the firing pin is on the short side of spec. You could also have the hammer spring installed improperly or have less than milspec hammer spring. Some aftermarket FCG produce insufficient hammer blow on hard military primers. This ia fairly common problem on 7.62X39 but Ive never experienced an issue with my 6.5 Grendel AR-15s and Wolf steel cased ammo.
The only other issue with failure to fire is where some manufactures have used 2.80 length bolts and shorter firing pins. If you replace the bolt with a 6.5 Grendel bolt like AA or the GB Monster 2.810 bolt and use a short firing pin you can get light strikes.
A milspec firing pin should measure 3.279 + or - a thousandth or two.
https://www.brownells.com/gunsmith-tools...26477.aspx
This issue has come up before where tolerance stacking causes light strikes. Some times the bolt overall length is greater than 2.81 and the firing pin is on the short side of spec. You could also have the hammer spring installed improperly or have less than milspec hammer spring. Some aftermarket FCG produce insufficient hammer blow on hard military primers. This ia fairly common problem on 7.62X39 but Ive never experienced an issue with my 6.5 Grendel AR-15s and Wolf steel cased ammo.
The only other issue with failure to fire is where some manufactures have used 2.80 length bolts and shorter firing pins. If you replace the bolt with a 6.5 Grendel bolt like AA or the GB Monster 2.810 bolt and use a short firing pin you can get light strikes.
A milspec firing pin should measure 3.279 + or - a thousandth or two.