LRH Team Member
- Dec 20, 2008
- Great Falls, MT
Did you plug in the right information?Berger twist calculator not work for tipped and mono bullets.
Below is Cayuga 117 bullet information (https://patriotvalleyarms.com/cayuga-hunting-projectiles/)
Optimal Freebore: 0.160"-0.210"
G1 BC average = 0.580*
G7 BC average = 0.282*
*The average BC was measured using 7tw 5R rifled barrels and being shot at approximately 2970fps. Different rifling geometry and muzzle velocity will affect the BC in a nominal manner.
257 cal Cayuga 117 requires a 1:8tw barrel.
... when plugged into Berger's SG calculator...
As you can see, it does work if the right information is plugged in.