twist rate for rebarreling .270

Discussion in 'Long Range Hunting & Shooting' started by amork, Aug 21, 2019.


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  1. amork

    amork Well-Known Member

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    I am rebarreling my .270 winchester this fall with a lilja 1 in 8 twist barrel to stabilize the berger 170 grain bullets. I am wondering if I want to shoot say a 130 or 140 grain bullet with the 1 in 8 twist what velocities am I going to be looking at ?
     
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  2. codyadams

    codyadams Well-Known Member

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    Probably won't change it too much. When shooting light bullets in tighter twists, I did not notice anything more than a 20-50 fps difference than what would be achieved with a slower twist designed for the lighter bullets. You usually pressure out earlier if anything though, I doubt it would be enough to concern yourself with however.
     
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  3. amork

    amork Well-Known Member

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    Thankyou,
    I didn't know if I was going to run into pressure or velocity issues when running the lighter bullets. I wish the .270's had a larger selection of larger bullets for the long range market. I just hope the 170 berger performs the same as their others after I get my rifle back and I probably won't ever shoot smaller bullets in it again anyway.
     
  4. codyadams

    codyadams Well-Known Member

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    Keep in mind, if for whatever reason you don't like the 170 Berger (so far they are working great for us), you can run a 156 Hammer Hunter monolithic. Not as high bc as the 170 (G7 of .292, G1 of about .570, vs. G7 of .339 and G1 of .662) but they have a reputation for extreme accuracy and fantastic terminal performance.

    https://hammerbullets.com/product/277-cal-156g-hammer-hunter/

    The only issues you would likely run in to is if you shoot the light varmint type bullets at high velocities, you may have issues with them coming apart. 130's and 140' should be just fine.
     
  5. Bill Cauley Jr

    Bill Cauley Jr Well-Known Member

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    63144E98-CEF5-4E1A-AAE4-3610413FD9DA.jpeg
    Not sure about velocity’s but here are hunting bullets from Burger weights and optimal twist rate is listed for most bullets a one in 10 twist is optimal with your barrel being a one in 8 you should be able to throw even the heaviest bullet
     
  6. .300 Dakota

    .300 Dakota Well-Known Member

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    I noticed no pressure or loss of velocity when firing a 1:9 25-06 with 1:10 data or with a 1:8 30 Nosler with 1:10 data. Now I am noticing some very slight shortcomings from a 1:9.5 338 Edge wildcat compared to 1:10 data, as well as from a 1:8 .260 Rem when using 1:9 data, but I'm wondering how much is due to the twist and how much is from the barrel itself. Some barrels are faster than others, even with the same twist and length. I don't think you'll notice IF you're missing anything.
     
  7. sedancowboy

    sedancowboy Well-Known Member

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    Brian Litz Has written about the effects of a faster twist barrel on velocity. His conclusion was that it has a very minimal effect. As I recall about 5 fps per inch of twist less velocity. I have found that the 1-8 twist does a better job of stabilizing the 150 gr bullets as well as the 170s. Don't be afraid to try the 130s-140s. We are having really good luck with the 145 ELD-Xs in a 1-8 if you don't need the 170s.
     
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  8. amork

    amork Well-Known Member

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    I think from what you guys are all saying I am confident with getting the 1 in 8" twist barrel. I can't wait till I get the barrel installed and get a load worked up. I am going to start with the 170 grain berger and work up a load for that and it all goes well I may try a 140 accubond or similar weight eld x for the speed goat and mule deer season. Just wish I could have it for this hunting season to test it out.
     
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  9. Lenny Foffa

    Lenny Foffa Well-Known Member

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  10. corsair4360

    corsair4360 Well-Known Member

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    I have a Winchester Model 70 left hand in 270 Winchester Short Magnum, which has a 1:8 twist barrel on it. The original barrel was a 1:10
     
  11. freddiej

    freddiej Well-Known Member

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    It's good to see someone else building a fast twist 270. Mine will be a 270 WSM but that is just because I think the WSM case will launch the 170 grain with much better velocities than the standard 270 Win. I was hoping to find a 1:7.5" or a 1:7" twist rate. I think that the 170's would perform better with the slightly tighter twist.
    have fun! shoot more!
     
  12. freddiej

    freddiej Well-Known Member

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    I have to know; how does your 270WSM work with the 170 slugs? or any slug 150 and above. How was load development? I have not seen/found any loads for anything over the 150 grain slugs. My 270 WSM rebarrel job will be happening early next year since I just do not have time right now to do it.
     
  13. corsair4360

    corsair4360 Well-Known Member

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    The heaviest bullet I have for my 270 WSM are 150 grains
     
  14. rbTanzan

    rbTanzan Well-Known Member

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    My wife recently got a new Tikka in 270 Win. She tends to like the 110TTSX and 129 LRX, so 10" twist has been fine. I have my eye on the Hammer Hunters at 156gn and 168gn, should she want to do elk with that rifle. That last bullet has a BC of G7 .266 from one test and .309 from calculated shot drops. Not too shabby.

    However, if I/she were to rebarrel her rifle, I think that I would recommend a 7" twist, since the 168gn benefits from a 7" twist. McGowen in Kalispell does such barrels, for one.

    As mentioned, the 156gn can use the 8" twist and you can calculate differences in drop and windage for both bullets. The extra speed (100fps?) on the 156gn may be all that is needed inside 500 yards. I think that windage for both will be about the same at 400-500 yards, while the 156gn may be slightly flatter, dropping about 2" less inches at 400.