Freebore

Chamber illustration indicating the various sections of a typical rifle chamber. The freebore is the cyan colored section just ahead of the neck.

In firearms, freebore (also free-bore, free bore, or throat) is the portion of the gun barrel between the chamber and the rifled section of the barrel bore. The freebore is located just forward of the chamber neck and is cylindrical in shape.[1][2] The diameter of the freebore is larger than the groove diameter of the gun barrel bore so that no rifling is present and projectiles used in the firearm can accelerate through the freebore without resistance.[3][4]

  1. ^ Zwoll, Wayne van (2011-06-01). Shooter's Bible Guide to Rifle Ballistics. Simon and Schuster. ISBN 978-1-62087-285-7.
  2. ^ Boddington, Craig (1999). Make It Accurate: Get the Maximum Performance from Your Hunting Rifle. Safari Press. ISBN 978-1-57157-150-2.
  3. ^ "Glossary – SAAMI". Retrieved 2019-05-05.
  4. ^ "Measuring Freebore, Bullet Extraction Force & Bullet Engraving Force". Retrieved 2024-02-11.