I found a calculation for twist rate and compared all the bullets I have used in my 6.5 Creedmoor and Hart .25-06 (converted from .270 WIN)
Twist rates
A longer bullet requires a faster twist rate for stability
Calculation: D2 x C/L= twist
D= bullet diameter squared
C= constant of 150
L= bullet length
Browning 6.5 Creedmoor Twist: 1 in 9"
Length Twist
Hornady ELD-M 147gr 1.462 7.2
Berger 140 Hunting 1.400 7.5
Hornady SST 140 1.398 7.5
Hornady ELD-M 140 1.397 7.6
Barnes Match 140 1.344 7.8
Sierra 140 SPBT 1.272 8.2
Hornady 140 SP 1.255 8.3
Speer 140 Hot Core 1.216 8.6
Most accurate have been last Sierra BTSP and Hornady SP
and both have the same impact point
Hart Barreled .25-06 Twist 1:9"
Hornady 120gr HP (new version) 1.178 8.4
Hornady 120gr HP (old version) 1.160 8.5
Nosler 120 Partition 1.166 8.5
Speer 120 BTSP 1.137 8.7
Speer 120 Deep Curl 1.121 8.8
Sierra 117 BTSP 1.113 8.9
Most accurate has been Sierra 117 BTSP
Have to redo both Speer bullets
Note: Bullets were measured from base to tip; true bearing surface would be base to ogive; not sure if that makes a difference
Twist rates
A longer bullet requires a faster twist rate for stability
Calculation: D2 x C/L= twist
D= bullet diameter squared
C= constant of 150
L= bullet length
Browning 6.5 Creedmoor Twist: 1 in 9"
Length Twist
Hornady ELD-M 147gr 1.462 7.2
Berger 140 Hunting 1.400 7.5
Hornady SST 140 1.398 7.5
Hornady ELD-M 140 1.397 7.6
Barnes Match 140 1.344 7.8
Sierra 140 SPBT 1.272 8.2
Hornady 140 SP 1.255 8.3
Speer 140 Hot Core 1.216 8.6
Most accurate have been last Sierra BTSP and Hornady SP
and both have the same impact point
Hart Barreled .25-06 Twist 1:9"
Hornady 120gr HP (new version) 1.178 8.4
Hornady 120gr HP (old version) 1.160 8.5
Nosler 120 Partition 1.166 8.5
Speer 120 BTSP 1.137 8.7
Speer 120 Deep Curl 1.121 8.8
Sierra 117 BTSP 1.113 8.9
Most accurate has been Sierra 117 BTSP
Have to redo both Speer bullets
Note: Bullets were measured from base to tip; true bearing surface would be base to ogive; not sure if that makes a difference