Tech Info

AR Gas System Lengths


For more information on available contours, visit our Contours page.


Contoured Blank and Prefit Contour List


Bullet/RPM/Twist Rate Calculator : This third-party ballistic calculator, while a quite useful tool, is meant only as a guide, and is not a hard-line means of establishing twist-rate.  Requires Excel, LibreOffice Calculator (Free) or another spreadsheet program capable of opening *.xlsx files.                       
          Determining accurate bullet measurements (caliber, weight, length, muzzle velocity, Specific Gravity) helps immensely with the accuracy of the calculator's results.  If you do not know your bullet's length, you can measure it yourself with a set of dial calipers, contact the bullet maker and ask, or look it up here and hope your particular bullet has a measured value listed.  If  you do not know your bullet's precise Specific Gravity (SG), you should be able to contact the bullet maker to determine this number, otherwise there are generic values included to represent certain bullet styles, however it is recommended to obtain as accurate a Specific Gravity as possible (SG is determined by the composition of the bullet).


For more information on available contours, visit our Contours page.


For any other questions, please refer to our FAQ page.


If your question is not answered there, please then Contact Us.