.308 1/10 or 1/12 help please

[blackfox]

As some may have seen im getting a .308 added to my licence (im a UK shooter).

Ive decided to start with a Remmy 700, either the SPS Tac or the SSD-AC.

Now what twist rate would be best??
It will be used mainly for deer and fox, but there will be target out to about 600yrds.

I know that with a 1/10 twist i will need to use the heavier bullets, but that would giuve me higher BC.
Any comments would be great, pros and cons of each.

Thanks

 

[Lowlight]

Re: .308 1/10 or 1/12 help please

I prefer the 1/10 for my 308s, I don't particularly like 1/12 as i don't shoot 168s...

If you look in the search box this topic was just debated at length so you should have no trouble finding it. If you do, try the site's google search that many use.

But I am not a 1/12" fan, as well I tend to have my 308s under 22" so the 1/12 is not going to help.

 

[223ai]

Re: .308 1/10 or 1/12 help please

School me on twist rate as relates to barrel length, if you don't mind. Is the thinking that the faster the twist, the better it is for short barrels?

 

[RADcustom]

Re: .308 1/10 or 1/12 help please

I have never had any trouble shooting lighter bullets out of a 1-10. 155 scenars have shot good for me in 1-12, 1-11.27, and 1-10.

You should be fine with the 1-10.

 

[RADcustom]

Re: .308 1/10 or 1/12 help please

The faster twist helps make up for the lack of speed to stabilize a heavier bullet from a shorter barrel.

 

[ORD]

Re: .308 1/10 or 1/12 help please

It all dependings on what bullets you plan on shooting out of your rifle, but I would get the 1:10 twist without a second thought based on that fact that you'll be able to run everything from lighter 145gr and 147gr stuff all the way up to 190gr (and possibly heavier) loads without a hiccup!

 

[223ai]

Re: .308 1/10 or 1/12 help please

Understood, thanks.

 

[Lindy]

Re: .308 1/10 or 1/12 help please

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I know that with a 1/10 twist i will need to use the heavier bullets, but that would giuve me higher BC.</div></div>

Well, not exactly.

You need a tighter twist to shoot heavier bullets, but that doesn't mean that you can't shoot lighter ones.

I have three rifles in .308 which have 1/12 twist barrels. All shoot everything up to and including 175 SMKs just fine.

I'd go with a 1/10 or 1/11 if I wanted to shoot up to 190s. You really don't want to go heavier than a 190 with a .308.

 

[223ai]

Re: .308 1/10 or 1/12 help please

Lindy -

Why would one not want to go heavier than 190 with a .308? Diminishing returns?

Thanks,
Josh

 

[ORD]

Re: .308 1/10 or 1/12 help please

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JPipes</div><div class="ubbcode-body">Lindy -

Why would one note want to go heavier than 190 with a .308? Diminishing returns?

Thanks,
Josh </div></div>

210gr subsonic loads.

(BUT...I know what you mean. It is silly to run heavier than 190gr from a 308).

 

[Lindy]

Re: .308 1/10 or 1/12 help please

Yes. As ORD noted, there is a point of diminishing returns, where the muzzle velocity gets too slow as you increase the weight of the bullet. With the .308, 190 grains is right on that edge.

If you need better ballistic performance out of a .308, you're better off to go with a higher B.C. bullet, of which there are several, rather than go much heavier than the 175.

 

[Graham]

Re: .308 1/10 or 1/12 help please

My AE barrel is a 12-twist, and it shoots Berger 185's and JLK 180 VLD's just fine.

But in my experience, and depending on temperature, a mass-produced Remington factory barrel 12-twist might not stabilize bullets with a longer bearing surface -meaning .30 cal VLD's over 175 grains.

Out to 600 yards you will only need 168 SMK's, but if you like to reload you will eventually try the heaviest bullet that your rifle will shoot accurately.

My 10-twist Bartlein shoots 155's quite well, but there is an optimum:

http://www.riflebarrels.com/articles/bullets_ballastics/bullet_imbalance_twist.htm

http://www.appliedballisticsllc.com/index_files/30cal_fullVersion.pdf?q=bullets

 

[Lindy]

Re: .308 1/10 or 1/12 help please

I thought we were talking about match-grade barrels here. Mass produced Remington factory barrels are best used as tomato stakes.

The Remington 5R barrel is a notable exception.

 

[223ai]

Re: .308 1/10 or 1/12 help please

Thanks for the information. Good data.

 

[Cegorach]

Re: .308 1/10 or 1/12 help please

On my build I went with a 1/10 so that I could play around with the 208 amax and other heavies. Additionally, it gives more flexibility for shooting different subsonic loads if you shoot suppressed.

I have heard something to this effect floating around on the board occasionally.

"You will always have problems under-spinning a bullet, but you will have far fewer problems over-spinning them"

When we are talking about a .308 you don't really have to worry about the latter too much because of the relatively mild velocities.

 

[ChadTRG42]

Re: .308 1/10 or 1/12 help please

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"> You really don't want to go heavier than a 190 with a .308. </div></div>
Lindy, just curous on this. If you can get a 208 A-max to 2570-2600 fps, it will have more drop, but have considerable less wind drift than any other 308 bullet. Since I normally know the distance I'm shooting, drop amount is not a big deal as the wind is. I had my 308 barrel (1:11" twist) chambered for the 190 and 208 A-max. Why would the 208 be a worse choice over you common 175 grain variety? Thanks!

Chad

 

[Lindy]

Re: .308 1/10 or 1/12 help please

Chad - I'd be really curious as to the pressure that load will develop.

If I'm launching a 175 SMK at 2675 from a .308, which is getting close to pressure limits, the equivalent speed in a 208 is going to be around 2450.

If it works for you, that's great.

Personally, I'd go to a 6.5 Creedmore before I'd try to push a .308 that fast.

 

[fdkay]

Re: .308 1/10 or 1/12 help please

If you are going out for fox, I would think that you might use a light weight varmint bullet in the 100 to 130 grain range. The 1-10" twist MIGHT be too fast for the real lightweight bullets. For a range out to 600 yards, a 1-12" will suit you just fine, it will stabilize the ubiquitous 168 grain match load which will serve you well out to 600. Most 1-12 will also stabilize the heavier 175 grain loads, but invidual barels vary.

If you go with the factory barrels, the new SPS that is pre-threaded for a a can comes with a 1-10 twist, the standard model comes with the 1-12 twist.

 

[bubbinator]

Re: .308 1/10 or 1/12 help please

I got into the 1/10 vs 1/12 issue in another post and started looking for barrels from all the major suppliers. The vast majority were 1/10s, the 1/12s were almost a special order item when you talked with them on the phone, and they all said 98% of what most shooters want to do with a .308 will be well srved with a 1/10. Hope this helps.