Optimum Bullet weight for 1:10 twist

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by scsims, Mar 25, 2008.

  1. scsims

    scsims Well-Known Member

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    I have a 28" 1:10 twist Encore Prohunter, and am having trouble getting the 168gr Bergers to shoot under 1.5". So I called T/C and they said for best accuracy out of a 1:10 twist 300WM I should be shooting 180gr bullet.

    Is there any truth to what they have told me?
     
  2. locotrician

    locotrician Banned

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    according to berger the 168 grains are intended for a 1:13 if your shooting 1:10 you can go with 190 or 210's easy.
     

  3. scsims

    scsims Well-Known Member

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    But will it effect accuracy if I'm spinning it faster than it needs to be?
     
  4. jwp475

    jwp475 Well-Known Member

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    Not exactly, I have a 30-06 and a 300 win both with 1 in 10 twist and they will shoot 165, 168 grain bullets very accurately.....
     
  5. davewilson

    davewilson Well-Known Member

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    if you lined up every 30 cal rifle out there i'll bet 95% of them are 10 twist. the twist rate is not causing less than exceptable accuracy. other bullets might shoot better. berger VLD's can be a little finicky. i'd say try some 200 Accubonds. if it won't shoot them, it's probably the gun.
     
  6. BountyHunter

    BountyHunter Writers Guild

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    Go to BR central and read Eric Steckers (from Berger bullets) comments about the new non VLD 30 cal bullets that they just came out with.

    basically, high BC, shoot good off the lands and and easier to tune.

    BH
     
  7. big honkin jeep

    big honkin jeep Well-Known Member

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    +1 my 1-10 30-06 and .300rum love the 165-168 gr bullets. They prefer the sgk and smks but the noslers shoot pretty well too.This seems to be the optimum weight/bullet combo in mine.
    Good luck Skip
     
  8. mphstigerfan

    mphstigerfan Well-Known Member

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    my 300 wsm loves 168 bergers but I like the heavier bullets better. I do know seating depth means everything with bergers. how far off the lands are you?? and what powder have you tried?? try the 185's if you have lost hope with the 168's, try 185's or 190's my gun liked the n550 with the 168's and the best powders with the 185 were n-165, rl19, and imr 7828. with 190's 7828 was the best by far. the vlds were 1thousanth off the lands and the 185 match bt's were i think 30 thou off
     
  9. flyin lizard

    flyin lizard Well-Known Member

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    My 300wsm likes the 175 bergers over R-17 and 180 AB's and 190 bergers over R-19, now the kicker, my c.o.a.l. is 2.891. My gun does not like bullets real close to the lands, I think the article to that fact is here on LRH..
     
  10. elkaholic

    elkaholic Well-Known Member

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    While it is true that over spinning the bullet will decrease accuracy, it is unlikely anyone but benchresters would care about the difference. Good bullets (concentric) should shoot well providing they have ENOUGH twist......Rich
     
  11. Kevin Thomas

    Kevin Thomas Well-Known Member

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    "Is there any truth to what they have told me? "

    To put it politely, Doo-Doo. In terms of pure benchrest accuracy, yes, you don't want to spin a bullet faster than necessary to achive about a 1.2-1.3 stability factor. For real world shooting, it's not an issue at all, unless you're using really bad bullets. Basically, spinning a bullet faster than needed accentuates problems in jacket wall concentricty. If the jackets are good, there's very little error to be magnified by the excess spin. If you're building a target rifle, and have the luxury of knowing preciesly what bullet you'll be using (often to the exclusion of all others, as in a Palma rifle) you can match up the twist rate very well. For most hunting applications, go with something that gives you some latitude in bullet selection.

    The 1x10" was originally intended in the 30 cal to work with 220 grain bullets, and has been handed down ever since, as much by tradition as any real ballistic requirement. It's still handle some pretty heavy bullets, but will also do a pretty good job with the light weights as well, assuming they're good quality bullets to begin with. I'm willing to bet you that with a bit of work and a little load development, you'll be able to get the 165-168 grain bullets (as well as some lighter ones, too) to shoot just fine. Enjoy.
     
  12. J E Custom

    J E Custom Well-Known Member

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    The 1 in 10 twist rate in .308 Dia Is an all round twist that will handel any bullet weight.

    As stated in other post the over rotation problem only occurs at or arround 3700+ ft/sec
    velocity and very few 30 cals will shoot them that fast.

    If you go to a 1 in 12 it may only shoot 168s and down. 1 in 11 is liked by people that shoot
    the lighter bullets (150- ).

    A 1 in9 is recomended if you want to shoot 200+ grain bullets in something like a 308 because
    velocity is very slow and the faster twist helps the bigger bullets stabilize.

    So optimum velocity for a 1 in 10 twist with any bullet weight would be 2600 to 3400 ft/sec


    J E CUSTOM
     
  13. Varmint Hunter

    Varmint Hunter Well-Known Member

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    Not to upset you but IMO 1.5" isn't bad for a ProHunter. There are many variables involved with 2 piece stocks and hanging forends. The 1:10 twist will stabilize most bullets up to 240gr so the suggestion to try a heavier bullet isn't a bad one. With a little luck you may get the groups down a bit. With the case capacity of the 300 win mag I'd prefer a bullet heavier than the 150gr regardless of twist.