Berger 80.5 Twist

[MGYSGT]

I am trying some 80.5 Bergers. I have 3 boxes. One of the 3 states 1:7 Twist and the other state 1:8 Twist. What's up with this??? Did they change something on the projectile? My barrel is a 1:8.

Tom

 

[Ned Ludd]

I am trying some 80.5 Bergers. I have 3 boxes. One of the 3 states 1:7 Twist and the other state 1:8 Twist. What's up with this??? Did they change something on the projectile? My barrel is a 1:8.

Tom

Berger has updated many of their bullet data files over the years. During that process, they have used slightly more conservative values for twist rates. From the Berger twist rate calculator (https://bergerbullets.com/twist-rate-calculator/):

Worst case scenario





Intermediate case scenario



You can see that with a velocity of 2650 fps, depending on the temperature and elevation, either a 7.5- or a 7.8-twist is necessary to maintain an Sg (gyroscopic stability coefficient) of 1.5 or greater. Increasing velocity will also have a modest effect on the minimum twist rate.

 

[JMayo]

My 6bra seems to like 90's better but the 80's were still 1 hole groups.

 

[MGYSGT]

Guess I should have said .223 with 80.5's

 

[snakepit]

When the Berger 6mm 105 gr Hybrids came out Berger said use a 1:8 twist and after a few years it was updated to 1:7 twist. As was previously stated use the Berger Twist Rate Calculator because there are too many variables to consider instead of just what the box says.