What is the bolt diameter on attachment holes in AR 15 rails?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Len Backus, Jun 26, 2010.

  1. Len Backus

    Len Backus Administrator Staff Member

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    May 2, 2001
    I mean the pre-threaded holes on a rail.

    I have a new crossbow that utilizes a rail. I want to attach a hand made handle thingy using those pre-threaded holes. I assume there is a standard dimension to them.

    Diameter and TPI???