Totally confused on twist rate programs

[Baddog0302]

With a time on my hands I started playing around with a new barrel project using different rate of twist programs. TOTALLY CONFUSED to say the least.
First , here is what I used ; , 1.185" long .308 lead bullet at 1100 fps.
A. McGowen's program suggested a 9.5 " twist, so round down to 9
with a jacketed bullet it suggests an 8.9 twist
B. The Don Miller program gave a 2.44 factor [1.5 th 2.0 are good]. A 1-12 twist
gave 1.7 or good
C. The JBM** gave a good with a 1.63 factor [1.3 th 2.0 are good] that is with the 1-10 data.
Both B & C do not ask for bullet material

 

[Lapua40X]

What bullet weight are you using in the formula?

 

[Baddog0302]

used 200 gn in all the programs

 

[Steve Ladino]

Hey maddog,
I haven't used a program to determine an appropriate twist rate for my 30 cal. lead 220 grain Lyman 311284 cast bullets but two of my 10 twist 06's shoot them fine, as does my .308 10 twist. They are 1.232" long. My muzzle velocity is 1500/1600 FPS. though which could be why they stabilize in my guns, at 1100 MV they may not.
Steve

 

[geo.ulrich]

if you give me data I can give you optimum twist and what your stability factor will be at a certain velocity. criteria I need bullet length, dia, nose or ogive length and b.t. length and angle or if flat base . I design bullets and make bullet dies so my program is alittle more advanced. also just for info weight has no bearing on twist..George I do not get on here much but will look back in morning.