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<p>[QUOTE=&quot;springfld.arsenal, post: 297605, member: 54&quot;]Thanks.&nbsp; Looking at it more carefully, I can see that the small flat areas would correspond to the bolt head being forced into an octagonal hole.&nbsp; The bolt has been used because the plating is absent from those little circles on the periphery of the head; the force-fit scraped the plating off and flattened the curvature where it was in contact with the octagon.&nbsp; The forced contact would provide plenty of resistance to turning so the nut could be tightened fully on the threaded end.&nbsp; I’m guessing this system was developed to facilitate machine-installation of the bolts since the requirement for a particular angular orientation to allow some kind of wrench to grip the head no longer existed.[/QUOTE]</p><p><br /></p>

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