6 BRA w/ 1:7 twis

Discussion in '6BR, 6BR Improved & Wildcats' started by gau17, Oct 7, 2018.

  1. gau17

    gau17

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    Is 1:7 twist too much for a 6 BRA? I see most people are using 1:7.5-1:8. I'm planning on using either 105 hybrids or 110 SMKs. Also what velocity can I expect out of a 26" barrel vs one that's 28".

    Thanks in advance.
     
  2. BenPerfected

    BenPerfected Gold $$ Contributor

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    If you look at the Berger twist rate chart it shows that a similar Berger bullet is stable at 7T. Seems to me that any unstable bullet should show on the paper.
    Ben
     
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  3. group therapy

    group therapy Silver $$ Contributor

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    Bunches of great shooters say 1-8 twist. Bunches and bunches. Did I mention it is a bunch of them;)
     
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  4. Puzzaz01

    Puzzaz01 Gold $$ Contributor

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    Yep, I tried the 1:7 twist and it was ok but not as good as what I was hoping for.

    Darrin
     
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  5. BRGUY

    BRGUY

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    Wouldn't the 1-7" twist rate work best with the longest and heaviest 6mm bullets, or would you need a bigger case to push the bullet harder and faster for proper stability???
     
  6. Willow

    Willow

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    Depends what bullets you want to run. I'm not convinced a 115gr pill is the solution in a BRA. It is VERY happy pushing 105-108gr pills between 2960-2990. I run a 30" 8 twist 5R Krieger and it's a beauty. No problem stablising any 105gr bullet and it loves the Berger 108s. I don't need to hotrod the cartridge to obtain these speeds, my loads are quite mild compared to some of the data I've read on here. For 115s...personally I'd be looking at something like the 6XC, 6 creedmoor etc to take advantage of the extra boiler room.
     
  7. SPJ

    SPJ Silver $$ Contributor

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    There is better Bullets than either of those you mentioned.
    1-8 Twist is the most common no need to over spin.
    My 28 inch barrel spits out 107smk at around 2860-2880
     
    Don likes this.
  8. sidecutter

    sidecutter

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    im using 1/8 in a brux 26 in. 108 bergers @2848fps
    it shoots real good
     
  9. Sheldon N

    Sheldon N Silver $$ Contributor

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    My 7.5 twist 26" Hawk Hill 6BRA ran 105 Hybrids at 2950 with 31.4-31.6 Varget. I'm now running at 2900 fps with 30.6 H4895 in the later life of the barrel, still shooting great. I tried the 110's and my barrel didn't like them.

    I would not run a 7 twist for 105 Hybrids, but it might not be a bad choice if you were set on running the 110's. You'd probably find those will want to run around 2850fps.
     
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  10. swd

    swd Yep that's me Gold $$ Contributor

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    It all depends on application. I have a 7.5" BRA and it shoots 110SMK's really well. It's a slow node at 2800 even. Even at that slow speed it still wins in wind drift against 107's at 3020. It shoots 107's and 110's equally very well so I use the 110's and enjoy better ballistics. For benchrest shoot whatever bullet you think will win. Pure accuracy is more important there than in F Class. Different games have different ultimate needs.
     
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  11. gau17

    gau17

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    Thanks for all of the comments. I'm hoping the 110's will shoot well for me. This rifle will be used at PRS type matches.
     
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  12. MDM

    MDM Silver $$ Contributor

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    I'm have two 7s and one 7.5 running 105 hybrids. Below 30 degrees and I start to lose bc with the 7.5. I run a 7 in 6-47 as well.
     
  13. johara1

    johara1

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    I would never go past 7.75 to 1 it is all you need with a 105, I tried 7.5 to 1 and they ran a little slower, 7 to 1... I think is out of the question. You reach a point of no return, I ran DTAC 115's out of an 8 twist and they shot good...... Again what do you seek in accuracy a.1 or 1/2" jim
     
  14. johara1

    johara1

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    I would bet you lost speed due to the cold, I would see if your speed dropped I shot 115's with the same charge as 70 degrees and there is a huge difference plus the density of the air..... jim
     
  15. MDM

    MDM Silver $$ Contributor

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    I should say I lose bc according to Berger’s twist rate calculator. It's marginal, and I'm assuming Berger knows there own bullets, but also realize those numbers are not set in stone based on variables like lands profile and number of grooves, etc. I have a kestrel and magneto speed that I use religiously. I always know what my velocity is at a given temp. Quite a bit of difference in a -1000 DA and 3500 DA for elevation. Just using the info for the 115 plugged into Berger's twist rate calculator, it shows the BC being compromised by 7% with an 8 twist at 30 degrees and 900 elevation. Again, maybe not exact, but enough to look into it and verify in the particular rifle.
     
  16. johara1

    johara1

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    Well you must have a lot of faith in Berger, they don't always tell the truth. I had hybrid bullets that went that went from .2428 to .244 they said it can't happen.... really, BC's that were way below what that was written on the box and on their site and well above the 105 hunting VLD.
    I was talking about the 115 DTAC would shoot in an 8 twist, I had 2" groups at 1000 with them, the 115 Berger I could never get to shoot good, so I used them for fire forming. I had 1 lot of hybrids that were very good and I am sure there are more but if you find one that is exceptional better buy the whole lot ... don't think they are all equal..... no matter what they tell you.... better check for yourself .... jim
     
  17. BRGUY

    BRGUY

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    It was a totally different ball game when Walt Berger ran the business! Walt was there to help any way he could. These other guys are just not quite as truthful, nor knowledgeable as what Walt was. At least in my experience with Berger bullets.
     
  18. FrankG

    FrankG

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    Pretty sure I’m going to chamber my new barrel in 6BR. It’s a 1-7 twist and I’ll see what it does. I’m going to play with bullets up to the 110 SMK.

    Had a 6 Dasher in a 1-7.75 twist and shot excellent.

    Later, Frank
    Bartlein Barrels
     
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  19. MarcusOlsson

    MarcusOlsson

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    I run my 95gr SMK in a 26" 7twist Bartlein 6BR
    It's what my gunsmith had at home and it's shoots like a dream running them at about 930m/s with n550
     
  20. 1shot

    1shot Site $$ Sponsor

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    I have a 32" 7.5 twist chambered in 6SLR. This is a 45. gr. capacity case and it runs 110 SMK's a little north of 3,100 fps. with stellar accuracy.
    I would think that the extra case capacity allows me to take advantage of all the BC the bullet has to offer.
    I hope this helps,

    Lloyd
     

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