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Long Range Shooters Discussion

Barrel Twist Rates - Long Range

Mosin Long Range Shooting Discussion. F Class and other topics such as equipment and more.

Barrel Twist Rates - Long Range

Postby Grindl » Mon Apr 18, 2016 12:39 pm

When building a Mosin cartridge ; .308 LR rifle , would there be any advantage to using a 1:11 twist barrel over a 1:10 twist barrel ? What kind of restrictions , or limitations would that create in selection of bullets , bullet weights , and achieving correct muzzle velocities using a 26" barrel of either twist rate ?
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Re: Barrel Twist Rates - Long Range

Postby Grimstod » Mon Apr 18, 2016 1:28 pm

Now that I have more experience with this stuff, I think in hind site I would have gone with a 1:12 twist. You will get better accuracy and who in tarnation is going to shoot a 230r bullet out of this case. Unless your doing subsonic stuff.

So to answer your question 1:11 is fine. Slower twist barrels are more accurate anyway.
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Re: Barrel Twist Rates - Long Range

Postby jaysny87 » Tue Apr 19, 2016 10:22 am

I think its important to weigh what matters to you in building a rifle. For me it really comes down to projectile selection. And naturally when building a custom rifle reloading is a must to realize the rifles true capabilities. there are several questions to ask yourself at the star. A heavier bullets with high B.C. needs higher velocity to achieve its advertised B.C. (does your cartridge allow for this?) What is realistically the longest range you plan to shoot? If its for hunting what is the size of the game you want to take? What volume of shooting will you do? After you have narrowed it down to a specific projectile for a purpose built rifle then you can select a barrel contour and twist rate.
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Re: Barrel Twist Rates - Long Range

Postby Grindl » Wed Apr 20, 2016 10:06 pm

The "Build" is a "F" Class type rifle with a Mosin action and 26" Kreiger-5R , Target Taper , .308 . Prone style stock w/Bipod . Vortex HST ; and I was asking for thoughts on varying twist rates . Some Matches limit the shooter to a maximum 155gr bullet .And higher velocities would come into play . I'm thinking of starting around 165/168gr area , and in the neighbor-hood of about 2,700-2750 fps out the tube . My standard Target, load would be a 175gr VLD using 4895 or Varget , and I've heard some good things about both HV-100 and BL-C for the lighter bullets in the higher velocity ranges .I guess I'm trying to decide which barrel twist rate would have more versatility in the 1,000 yard range .
With these basic parameters , the question of 10 or 11 twists came into play , and there are some pretty good LR shooters on this site that can offer proven knowledge on making a barrel choice on a rifle I'll be shooting "F" for a few years .
Sorry for not being clearer in the initial post as I wasn't trying to start a debate . Easy to do when twist rate comes into the discussion . Left it a little to general ....Opps !
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Re: Barrel Twist Rates - Long Range

Postby ShootnMathews » Mon Apr 25, 2016 2:39 am

If 150-175 grains is your target range for bullets then a 1:11 twist should be just fine. You won't need to go to a 1:10 twist unless you are planning to shoot 185 grain or heavier bullets.

I don't shoot f class so I don't know the rules but I do know the higher BC bullet you shoot the better off you'll be at long range. Mostly because of the less wind drift. Bullet drop is easy to calculate and adjust for. Your ability to read the wind and adjust for it is what separates the men from the boys at long range. A higher BC bullet has less wind drift which gives you more room for error in your "read" of the wind. A 210 grain high BC bullet may drift 5" per 1 mph at 1000 where as a 150 grain bullet might drift 10" per 1 mph. So that makes your calculation far mor critical. Those are just estimate values, I didn't check my charts. I would shoot the highest BC bullet they will allow you. (I'm sure they don't have a cap on BC, but BC is directly related to weight which they may have a cap on, as you mentioned).

Good luck
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Re: Barrel Twist Rates - Long Range

Postby Grindl » Wed May 11, 2016 1:59 am

The responses are appreciated , as I know the information is field and range proven from you guys . I will be staying below 185gr bullets , and I had just learned about certain matches having bullet weight restrictions before my last post .
I remember some time back , 0933 saying he had very good results with Berger 155gr VLD and BLC-2 and also HV100 . I'll have to dig back into the posts for his recipe on them .

No more than get one rifle shooting good with a matched-up load , and now I'm starting all over again with a completely different set-up , in a different gun , that's not even built yet .Think we all have a little streak of masochist in us . :roll:
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