Rate of twist?

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regulate34

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I am looking at a new rifle. The rifle has a 20.5" barrel with a 1-12" ROT. It is in 30-06. From what i read most 30-06 come in 1-10" ROT to help stablize heavey bullets such as 220grain. Is the 1-12" going to give issues with 180grain bullets? The 30-06 i shoot now likes 165grains. Its a parkerhale but i do not know the ROT. It did not like the 180grains so much. I presume with a 1-12" ROT the 200g and 220g would be out of the question?

Any insight or advise would be great as i am new to the insides of rifles.

thanks
 
My .308 Norma Magnum has a 1-12 twist and shoots 180gr bullets just fine .Have never tried or needed heavier bullets................Harold
 
The 1-12" twist in a 30-06 will stabilize most bullets up to and including a 200 grain flat based version.
180 grainers are no problem at all.
Regards, Eagleye.
 
regulate34 said:
I am looking at a new rifle. The rifle has a 20.5" barrel with a 1-12" ROT. It is in 30-06. From what i read most 30-06 come in 1-10" ROT to help stablize heavey bullets such as 220grain. Is the 1-12" going to give issues with 180grain bullets? The 30-06 i shoot now likes 165grains. Its a parkerhale but i do not know the ROT. It did not like the 180grains so much. I presume with a 1-12" ROT the 200g and 220g would be out of the question?

Any insight or advise would be great as i am new to the insides of rifles.

thanks
Click to expand...

Recommended twist from Shilen:
.308
- 7" * for heavy VLD bullets and/or subsonic ammo.
- 8" for bullets heavier than 220 gr.
- 10" for bullets up to 220 gr.
- 12" for bullets up to 170 gr.
- 13" * Ratchet rifled 4 groove
- 14" * for bullets up to 168gr.
- 15" * for bullets up to 150 gr.
- 17" * for bullets up to 125 gr.

But as posted earlier - 180 grain flat base bullets will not be a problem... VLD heavy bullets probably not. 200 and heavier probably not. You can always try a heavier bullet and if accuracy is terrible you know why.
 
Here is a little piece of info.
Many 308 Winchesters are rifled 1-12"

Factory ammo is available up to 200 grains.
I have yet to see a 308 that would not stabilize these 200 grain pills.

Granted, most are semi-spitzer, so a bit shorter than a true spitzer.
But the 308 only drives these to 2400+, so quite slow.

I have owned at least 3 European 30-06 rifles with 12 twist barrels.
They all shot the 200 Partition and the 200 Speer just fine.

In fact, using the Greenhill formula for calculating twist, the 200 Partition
which is 1.345" long, requires a minimum twist of 1-12.6"
The 200 Speer, which is shorter at 1.272, only requires a 1-13.3" twist

Many Norma Mags are 1-12", but of course, they do drive these bullets faster.
However, speed is a lesser factor than bullet length when it comes to stability.

Regards, Eagleye.
 
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Ok what i have gathered is i am going to get the gun and the 1-12" is not going to be a issue for what i intend to shoot. thank you guys
 
I've shot 180 RN handloads out of a 1-12" Win 94 30-30 and they hit nose first.....Slow enough for you?
 
Eagleye said:
Rotation RPM does not drop off much, so stability remains.
Eagleye.
Click to expand...

I gathered that...

What I got from hometownhero's post was, longer bullets can be stabalized with a slower than required twist rate so long as you can push it fast enough through higher velocity...This is why I asked....
 
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I just read the following article the other day, it may be of interest to you. For what it's worth, this guy suggests muzzle velocity has very little impact on stability when compared to twist rate. He was using a 1 in 13" twist rate.

http ://riflemansjournal.########.ca/2010/06/ballistics-heavy-bullets-in-113-twist.html
 
A .308 Winchester with a 1-12" twist will stabilize Sierra 190 Matchking bullets.

A 190SMK is a *long* bullet; any hunting bullet you have that is shorter than a 190SMK, should stabilize in your .30-06.
 
captonion said:
I gathered that...

What I got from hometownhero's post was, longer bullets can be stabalized with a slower than required twist rate so long as you can push it fast enough through higher velocity...This is why I asked....
Click to expand...

It works for me in my gun. And from What I have read it should work in others as well. I shoot some bullets that the recommended twist is faster then what I have and shoots darn good with enough speed.
 
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