[savage_man]

hey,
Could anyone clear this up for me? If so it would be a great help.
Could you tell me the hole rate of twist thing like: 1 in 10" is what my new savage modle 111 in 30-06 has (and i love it) is that a good thing for longer range shooting? Or is 1 in 10" a bad thing for longer range shooting?
By longer range shooting i mean 500 too 800 yards.

thanks

 

[morpheus]

From what I have heard, a longer twist rate with a .30-06 is better. I belive if you want to shoot long range a 1 in 21 inch twist rate is good. But I'm probably wrong because I heard my friend talk about it a couple of months ago.

 

[mele]

Err, sounds like some bad data.

Rate of twist determins what weight bullets that will be stabilized with a give cartridge. There is actually a formula out there to calculate what ROT is needed for a given caliber and bullet weight (but I forget the formula). The heavier the bullet, the more RPM you need to stabilize it, so a faster rate of twist is needed. (faster meaning, one twist in LESS distance). For .308, if you are shooting 175+ then I generally recommend 1:10" (or 1:11" if its an option).

Your 1:10" works great for just about all common weights shot with the -06

MEL

 

[morpheus]

Yeah, I probably miss heard him. My fault.

 

[mrotherstuff]

Are there stability issues with using a light bullet in a fast twist rate? Say I use 145 grain in 308 for 1:10 twist.

 

[JLU]

Here is the Formula I have for Twist Rate.

Bullet Diameter = A
Bullet Length = B
Bullet Ratio = C
Bullet FPM = D Use 150 for (2500 to 2800 FPM) or 180 for (>2800 FPM)

C= B / A
Twist Rate = D x (A / C)

JLU

 

[mele]

THanks JLU, that looks like the one I remember.

In terms of lighter bullets with faster rate of twist barrels. Yes, there can be cases of "overstabilization" with light bullets, but the cases are generally extreme. You "should" be fine with a 145 in a 1:10 twist, but notice I said "should" as I have not fired any bullets that light through my .308 rifles.

MEL

 

[madgunsmith]

Barrel twist formula

Professor Greenhill taught artillery at the British Army's military acadamy in the 19th century.

Greenhill researched barrel twist and through empirical study he came up with this formula.

Bullet length (in calibers) multiplied by twist rate (in calibers) should equal a constant. The constant is 150.

Here is an example:

You want to stabilize a .264 diameter 155 grain Sierra Match King. This bullet is an inch and a half long. The length of this bullet in calibers is 1.5 divided by .264. The length of the 155 grain .264 Sierra Match King is thus 5.68 calibers.

150 divided by 5.68 equals the twist rate in calibers.

To stablize a .264 diameter 155 grain Sierra Match King, you need a barre with a twist rate of 26.4 calibers.

26.4 multiplied by the caliber, .264 equals the barrel twist in inches.

You need a twist of 1 turn in 7 inches.

When determining the ideal twist rate, it all depends on the length of the bullet that you intend to use. Longer bullets need a faster twist.

Hope this helps.

Madgunsmith.

 

[Savage+Nightforce]

so what is a good rate of twist for a .308 and 168 bthp ammo

26 inch savage 10fple not sure what twist rate is...1 in 10 i think?????
shooting black hills ammo... not sure of velocity

 

[mele]

For 168 1:10 and 1:12 will both work. if you ever plan to shoot 175's, it might be best to go with a 1:10" barrel

MEL

 

[Jeff_850]

the Remington 700P will stabilize a 175 gr BTHP in its 26" barrel w/ a 1:12 twist, some people say boarderline but this round has performed great in my rifle
1:10 twist is standard onthe 10 FP LE for .308s