Just went through this yesterday with a customer for a 30-.06 rebarrel wanted a 12 instead of the usual 10.
He wanted a wide range- from crazy light 135's to 200's, the calculator said they'd all work. Got dicey with 220's though.
The Berger twist rate calculator is great but correct me if I'm wrong it only works with Berger Bullets. I didn't realize that the bullet profile affected the stability factor so much. For example at my projected velocity the .30 caliber 185 Berger hybrid comes in at 1.22 which is not optimal while the Berger 185 Classic Hunter is very stable at 1.57 on their scale. Guessing it has to do with bearing surface? My rifle shoots 180 Sierra Match Kings (discontinued) at 2890fps (LabRadar) and is very accurate. My question is about Nosler Ballistic Tips. Judging from the responses here I think the 180 Ballistic Tip will be fine. Thanks to all who responded.
The Berger twist rate calculator is great but correct me if I'm wrong it only works with Berger Bullets. I didn't realize that the bullet profile affected the stability factor so much. For example at my projected velocity the .30 caliber 185 Berger hybrid comes in at 1.22 which is not optimal while the Berger 185 Classic Hunter is very stable at 1.57 on their scale. Guessing it has to do with bearing surface? My rifle shoots 180 Sierra Match Kings (discontinued) at 2890fps (LabRadar) and is very accurate. My question is about Nosler Ballistic Tips. Judging from the responses here I think the 180 Ballistic Tip will be fine. Thanks to all who responded.
Yes as cornhusker stated You enter your own bullet data. The length, weight and BC. Don't forget to change temperature to your average as well as your altitude.