Twist rate specification

[SteveOak]

In the C.I.P listing for a 260 Remington, http://www.cip-bobp.org/homologation/uploads/tdcc/tab-i/tabical-en-page97.pdf it has a twist rate, u, of 229 mm = 9.01".

Is that a requirement like the other dimensions?

 

[mikecr]

Seems an attribute of their proof barrel.
Your twist needs come down to the field air densities and bullet you're challenged with.

 

[barefooter56]

SteveOak,
Mikecr nailed it. Go to the Berger Bullet website and under the BALLISTICS tab on our main page . Click on TWIST RATE CALCULATOR in the drop down and enter you information there. Be sure to use the G7 BC if its a boat tail bullet, G1 if its a flat base. Be sure to enter the correct or as close to correct altitude of the area you are shooting in. The National Weather service website and a zip code can help here. This should get you started.

 

[SteveOak]

Thanks for the replies but hat was not quite the question. Rather than a 'what twist rate should I use question" it was a C.I.P. Standards question.

Is the twist rate stated in the C.I.P. a requirement for producers of firearms such as the other dimensions that will permit a C.I.P. compliant cartridge to chamber in a C.I.P. compliant rifle or is it optional/ recommendation kind of thing?

In the SAMMI book it says "optional" for twist rate but no such modifier is present in C.I.P. documents.

Thanks!!