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.308 barrel twist rate

robertsma

Private
Minuteman
  • Oct 4, 2011
    92
    15
    Phoenix / San Diego
    I am looking at either a bartlein, krieger, or rock creek at the moment and I have heard many different things on twist rate. I plan on shooting 168gr HPBT's that I either handload or use FGMM to shoot. .308 cal. What is the best twist rate, from what I have seen on here 11.25 is very common but I have a USMC gunner saying that our sniper rifles are 1-10. Just curious as to which atcually shoots better. Thanks
     
    Re: .308 barrel twist rate

    if you're dead set on 168grn then a 1/12 will be good enough and I wouldn't worry about it. However if in the future you'd like to go with something heaver than 180 then the 1/10 may be more your speed.

    I've got a 1/12 in my 700 PSS and it will stabilize anything up to 180grn so far (those 180's are the VLD berger's) but I've regularly shot 175's with no problem...actually those shot very well.

    as to why the military uses 1/10...probably so they can use the same blank for 300 mag and 308.
     
    Re: .308 barrel twist rate

    As I understand it the M24 uses a 5R 1 in 11.25 which is supposed to be optimum for stabilizing 175gr bullets. Don't know what twist the M40 uses. 1 in 10 is a common twist for 30-06 and .30 cal magnums, which are more often loaded with bullets with bullets over 180gr.
    My rifle has a 1 in 12 which is probably the most common factory twist for .308win, it does an excellent job with 168s and fair with 178s.
    Bear in mind however that over spinning a projectile is rarely a concern until they start coming apart in flight.
     
    Re: .308 barrel twist rate

    I would go a 1-10 twist. 1-12 is best for 168gn but if your going to want to shoot longer ranges youll need to go a faster twist then 1-12. 1-10 stabilizes up to 185gn well and still stabilizes 168gn well I still shot under moa with a 168 in a 1-10 in a sporter barrel
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: robertsma</div><div class="ubbcode-body">so in all reality the twist rate isn't super important in the long run unless you plan on shooting heavier bullets, is that basically the gist of it? </div></div>

    In commonly availible .308 twists, yes. They'll all generally do fine with 155-180 grain bullets.
     
    Re: .308 barrel twist rate

    I'm still kind of new at this so I'm limited on personal experience. However, the instructor at the basic sniper/observer course I attended recommended a 1-10 twist for .308 168gr HPBT. That's what I'm getting mine in.
     
    Re: .308 barrel twist rate

    I've found 1:12 will handle the 208 Amax and 208 HPBT from Hornady. So.... 1:12 is fine for a 308.

    That said, I will ALWAYS choose more, rather than less twist. For a 308, sign me up for 1:10 when I've got a choice. The drawbacks of "too much twist" are far, far, far smaller than the drawbacks of no enough. Not to mention, the extra drift/drop based on the gyroscopic stabilty is a "deterministic" factor, meaning it is completely calcualbe.
     
    Re: .308 barrel twist rate

    i like the 1:10 178 amax work really well in it, i have a 300 WM with 1:10 i shoot 208 amax out of but i believe im my opinion that the 208 is little big for the 308 unless you shooting <300 yrds
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AMTeam4</div><div class="ubbcode-body">I have a Bartlein 1-11 barrel and it shoots 168's and 175's ridiculously well.

    </div></div>

    ^^^ The direction I went as well. Do a Google for an online ballistic calculator and find one that takes twist rate into effect and calculates stability factor.

    Run some of your expected loads through there. It's not as good as real world experience putting rounds through barrels, but a hell of a lot cheaper, and a reasonable way to see the data for yourself.
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: robertsma</div><div class="ubbcode-body">I am looking at either a bartlein, krieger, or rock creek at the moment and I have heard many different things on twist rate. I plan on shooting 168gr HPBT's that I either handload or use FGMM to shoot. .308 cal. What is the best twist rate, from what I have seen on here 11.25 is very common but I have a USMC gunner saying that our sniper rifles are 1-10. Just curious as to which atcually shoots better. Thanks </div></div>

    Good variety on any of your barrel choices. I'm a little biased so stick with Bartlein if you can. Plus Bartlein can get you a twist rate that goes into any fraction that you want that goes out to 4 digits.

    If you have the option for 168's or 175's smk try to go with the 175's. 175's fly better out to 1K than the 168's do. You'll be hard pressed to get a 175 smk with Varget not shoot well out of your 308. Try that combo and start with .018 off the lands. Many 308 shooters in our club report back that .018 is a good starting point. Also try Berger 185 BT not the VLD...but the BT. They have a very high BC.

    With regards to twist rate, there is a standard, like 1-10 twist, that will accommodate many different bullets, but it depends on how anal you want to be. If you want to split hairs like I do, pick a bullet that you have your heart set on and get Bryan Litz's book on Applied Balistics that will tell you what is the optimum twist rate for the specific bullet you want to shoot (or ask someone here on the forum that has his book). You will have the best chance at getting it to shoot the way you want. Not saying that a 1-10 twist barrel will shoot better than a 11.25 twist or vice versa...just the opportunity to have the "optimum" spin on the bullet, based on weight, bearing surface, etc. will be based on accurate mathematical calculations and not someone's opinion.

    If you are going to try a variety of bullets, go with the fastest twist based on the selection of your bullets that you intend on trying out.

    Lastly, if you are dead set at using 168's, ask your gunsmith about 308 reamer selections. Every bullet/cartridge selection has an optimum freebore length based on where the bullet is seated in the powder column for optimum accuracy. If he can't tell you what it is, call Dave Kiff at Pacific Tool and Gauge and ask him. He'll be happy to let you know what it is.

    If your gunsmith doesn't have that reamer, or something very close to it, you may want to purchase it and send it to your gunsmith along with your barrel. Be sure to also mention, should you talk with Dave, what kind of magazine box (BDL, AICS mag, single shot, etc.) and bullet selection you intend on using. This makes a huge difference! You don't want the freebore too long (optimum for specific bullets) and the bullet not fit in your mag box and/or end up having .100 jump to the lands.

    Sorry for the long winded opinion.
     
    Re: .308 barrel twist rate

    I would go with 1:11.25" so you can shoot either 168gr or 175grs.

    You don't need a 1:10" twist unless you are going with a short barrel, eg 18". You want just fast enough of a twist to stabilize the weight of bullet, more is not better as you compromise accuracy and barrel life. The faster the twist, all things being equal, the shorter the barrel life.

    1:10" twist is not needed until you get to bullet weights greater than 210-220grs, which is not ideal for 308win because it doesn't have enough case capacity to push those bullets fast enough to optimize performance. That's why many 300wm have 1:10" twist because they use projectiles at that weight range, but have more capacity than 308win.

    I agree that the army likely chose 1:10" twist for their 308win, not for performance, but rather because of cost savings with running the same blanks as their 300win mags.
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: robertsma</div><div class="ubbcode-body">Either wat I just ordered a barrel today. Krieger 30 cal blank, 30' 5R, SS 1-10 </div></div>

    Good choice, I'm waiting on my heavy palma 1 in 10 now. Don't get hung up on 168's though, there are better choices. Now that you've decided on twist rate you need to figure out what reamer and again bullet choice is deciding factor, talk to smith who is chambering your barrel and figure out what bullets you're going to use. I like the 175 SMKs better than 168s and then you have Berger 185 either hybrid or BTLR and maybe 208 AMax. I plan to work up a load for my new rifle/barrel with 185 hybrids, will look at other options if that doesn't work out.
     
    Re: .308 barrel twist rate

    The 168's are a waste of time, they were designed for 300 meter shooting. The newer designed 155 class bullets fly better than the SIE 175's and the best barrel twist for todays bullets is 11.25 and 12 twist.
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: robertsma</div><div class="ubbcode-body">I am looking at either a bartlein, krieger, or rock creek at the moment and I have heard many different things on twist rate. I plan on shooting 168gr HPBT's that I either handload or use FGMM to shoot. .308 cal. What is the best twist rate, from what I have seen on here 11.25 is very common but I have a USMC gunner saying that our sniper rifles are 1-10. Just curious as to which atcually shoots better. Thanks </div></div>
    My 700 SPSS with 12 twist shoots a bit better than my 700 Sporter with 10 twist, all the way from the 155AMAXs to the 178HPBTs. But, the SPSS is a heavy barrel, 9oz Jewell trigger, it fits my rest better, etc etc.
    265705-R1-22-23.jpg

    Picture001.jpg
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Beef</div><div class="ubbcode-body">As I understand it the M24 uses a 5R 1 in 11.25 which is supposed to be optimum for stabilizing 175gr bullets. Don't know what twist the M40 uses. 1 in 10 is a common twist for 30-06 and .30 cal magnums, which are more often loaded with bullets with bullets over 180gr.
    My rifle has a 1 in 12 which is probably the most common factory twist for .308win, it does an excellent job with 168s and fair with 178s.
    Bear in mind however that over spinning a projectile is rarely a concern until they start coming apart in flight. </div></div>My 1 in 12 twist SPSSS shoots both the 168AMAX and 178HPBT pretty well.
    2011-10-26-76657.jpg

    2011-10-26-79226.jpg
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CanTarget</div><div class="ubbcode-body">Go to bergerbullets.com, they suggest 1:13 for 168-175, 1:12 for 185's. They show the 1:10 for 215,230's. </div></div>

    This is probably the most accurate guidance - pick the twist ratio based on the heaviest of the bullets above you plan to shoot.
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jhnmdahl</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CanTarget</div><div class="ubbcode-body">Go to bergerbullets.com, they suggest 1:13 for 168-175, 1:12 for 185's. They show the 1:10 for 215,230's. </div></div>

    This is probably the most accurate guidance - pick the twist ratio based on the heaviest of the bullets above you plan to shoot. </div></div>

    It is not the weight of the bullet but the length of the bullet that matters.
     
    Re: .308 barrel twist rate

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SIE107</div><div class="ubbcode-body">The 168's are a waste of time, they were designed for 300 meter shooting. The newer designed 155 class bullets fly better than the SIE 175's and the best barrel twist for todays bullets is 11.25 and 12 twist. </div></div>
    I really glad someone else has posted about this, as there are a number of guys on this board, that believe, and post that the heavier bullet (all things being equal-general shape etc) will always have the higher BC! I love the Berger 155's, started using them when the SMK's got hard to find, these are good bullets! The Palma guys shoot the 1:13, I'm shooting a 1:12, so far no problems.
     
    Re: .308 barrel twist rate

    Ford or Chevy? Here's my single data point: I'm using a bone stock Remmy 700 LTR with 20" 1:12 bbl. Deadly accurate with 175g SMK handloads out to about 1100 yards. No problem ringing torso-sized steel at 1000 with regularity. The only reason I see for a 1:10 bbl (with 308) is if you're shooting heavy subsonic stuff for a suppressor. (Now ducking for cover)