01-27-2014, 07:35 PM
The important measurement is the distance from the back of the lugs to the face of the bolt. Measure the length of the lugs and subtract the depth to the face.
On a 5.56 it should be .153-.156" mil spec. With the grendel it should be .143-.146"
On a 5.56 it should be .153-.156" mil spec. With the grendel it should be .143-.146"