Rate of twist

[dkchris]

In the market for a 7mm-08 that will be shooting 140 to 150 gr. stuff. Any info on the best ROT would be appreciated.

 

[car94401]

Here you go. This link should give you the best ROT breakdowns. Cheers.

http://www.shilen.com/calibersAndTwists.html

 

[dkchris]

Well that was painless. I guess ya just have to ask them that knows. Thanks for the info.

 

[jed]

There is also Greenhills formula where if you know what bullet you want to use, you can measure the overall length. Then compute.

Greenhill states that twist is equal to (150) times D2 divided by L

D is the bullet diameter in inches and L is the length of the bullet in inches.

For example the Speer 145 gr Grand slam measuers 1.118
Diameter is .284

therefore twist equals
150 X .284X.284 / 1.118 or twist equals 10.8

the theory is then for if you want to use the Speer Grand Slam then you should be using a 1 in 10.8 twist

I don't know how scientific it is but it works in my rifle. Cheers Jed

 

[dkchris]

Thanks Jed the more information the better. I'll give it a shot, so to say.

 

[.308--win]

My 7-08 has a 1 in 9.25" twist and shoots 140grn bullets great!

Perry