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+--- Thread: help me understand bolt measurement,,,, (/showthread.php?tid=7164)
help me understand bolt measurement,,,, - dammitman - 01-26-2014
so i have been following the barrel discussion and thought i would ask how to understand how to measure my grendel bolts. i understand they need to have the proper space where the shell sits to properly chamber that shell into the chamber. i have a bolt that measures from the lugs to the face at .136 and i also have a different one that measures only .128. i know i should have looked up the correct names for the parts of the bolt but carry me here. i will bet that i should have to measure from the other side of the lugs,,
help me understand bolt measurement,,,, - Lead Chucker - 01-26-2014
This is my understanding of it. The top of the bolt face(where it touchs the barrel face)should be flat, no hight spots. So no matter where you set your calipers to measure you should get the same measurment. But, some are not, I have two bolts that measure different depending on where you set the calipers on the bolt to measure. One bolt doesnt care if the calipers are on the lugs or not it measures the same from anywhere. The other I get different measurements depending weather the calipers are on the lugs or measured from between the lugs. That means the tip or outer part of lugs(the face part that touchs the barrel face)are higher than the part closer to the center of the bolt face. That said you shouldnt have .007" differents in that i would think. Im seeing .003" to .004" depending on where I measure from. Thats the best way I can explain it without a picture. sorry
help me understand bolt measurement,,,, - woohoo - 01-27-2014
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"