Getting 243 AI But Which Twist Rate

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by mjbine, Feb 20, 2008.

  1. mjbine

    mjbine Active Member

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    I was think about getting 1:8 twist and was going to shoot DAC 115gr or 107gr SMK but with 1:8 what would be the lightest bullet I could shoot?

    Also what would be better 26", 28" or 30" barrel. I heard there is not much difference in fps between 26 to 30. Is that true? I am just starting out and reading as much as I can to learn.

    Thanks

    Mike
     
  2. James Jones

    James Jones Well-Known Member

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    Mike you can shoot the 55gr Nosler ballistic tips out of a 243 Ackley with a 1-8 faster than the bullets can stand , mine I could get right to 4000fps before they would blow up , I had better accuracy with the 75gr V-max at the 3700-3800 fps range than the 55gr bullets though. I think that the 1-8 is the best twist for that case as it allows you to use about every bullet out their.
    As for the barrels I'd get the longest barrel you can , if you get a heavier barrel with the long 4"-5" shank that will allow you to cut a couple inches off the rear end and rechamber after the throat gets worn.
     

  3. adam32

    adam32 Banned

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    I'm getting mine built with a 1/8 Broughton 5c. I am going to shoot the 105gr Bergers, and probably the 87gr V-max, maybe the 75's also. It should be done it about 2 months, so I'll post what I find out.
     
  4. JLR

    JLR Well-Known Member

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    All the ones we've built recently have had 1/8. The only one that has a problem shooting lighter bullets is one Lilja....it likes to eat the 87gr V-max. The other Lilja, Krieger, and Broughton all shoot the small bullets just fine. We've recently pushed the 62gr Varmint Grenades over 4000fps through the Broughton. They all seem to really like the 105 Bergers though.
     
  5. uncleB

    uncleB Well-Known Member

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    The reason that your one Lilja is "eating 87gr V- Max" is most likely because it is a three groove barrel (if you want to really see bullet blow up try the 105 A-Max in this same barrel).
    The Krieger is most likely a 4 groove and most of the Broughton 6mm barrel's I have seen have been 5 groove barrels.
    IMHO with a 1-8" twist in a .243 barrel with this much case capacity, I will never use any thing other than a 5 or 6 groove barrel again.
    UB
     
  6. JLR

    JLR Well-Known Member

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    uncleB, I agree with your conclusion, but it's only one of the two Lilja's we have that eats the 87's. Odly enough, we actually use the 105 A-maxes for fire-form loads and they shoot pinholes out of that same barrel. Don't think TMR has tried to push them out of a formed Ackley round though.
     
  7. TMR

    TMR Well-Known Member

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    mjbine,

    If you go with anything other than a 3 groove barrel in the 1-8 twist, you should be able to use the lighter bullets. My Lilja barrel has a pretty tight bore and most of the 87 gr bullets don't make it to the target, and the ones that do....well, I could throw them more accurately. Put a 105gr berger in that barrel and it shoots in the .2's all day long. My fiance's Lilja shoots all bullets, but it also takes about 2 grs more powder to get the same velocity. The Kriegers we have seem to shoot any bullet, and the Broughton is extremely happy with anything that you feed it. Like my brother said, we had the 62gr Varmit Grenades shooting at almost 4100fps and the shot around a 1/4" group at 100yds. As far as the longer barrel.....my dad has a 26" barrel on his and gets about 75fps less than our 27.5"-28" barrels. After playing with this last broughton, I would like to get a 30" to test. I am running the 105's at 3300 out of a 27.5" barrel and have not hit max load yet....you can actually load another bullet and put it right back into the chamber.

    I think the barrel length depends on what your overall goal for the rifle is. If it is going to be on the bench shooting targets or varmits, then definitely a 30". If you want it more portable, then I would go with 27-28" varmit contour. The 243AI is a great round with the new VLD style bullets.
     
  8. TOM H

    TOM H Well-Known Member

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    I've got a dumb question if your shooting the VLD I would assume they are throated for them and if your shooting 55/60gr bullets how many rds before you see throat erosion vs if you just shot VLD bullets? If your shooting 60 plus grs bullets whats the groups at 3/4/500yds as compared to the VLD bullets there has to be some trade off I would think instead of a 1/8twist shoot all bullets. I fully understand the difference in barrel,grooves etc.
     
  9. mjbine

    mjbine Active Member

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    Thanks for the replies. What is a good load for fire forming the 243ai brass?

    thanks again.

    Mike
     
  10. Sendero_Man

    Sendero_Man <strong>SPONSOR</strong>

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    here is what I have... specs include fireform load....

    243AI Rifle Specifications:

    Winchester Short Action Push Feed (Originally M70 heavy varmint in 22-250)
    Broughten Medium Palma Barrel 1/8 twist 5 L/G 30 inches long
    Action blueprinted, magazine box modified for proper feeding, 4+1 rounds.
    HS Precision Winchester varmint stock, skim bedded with marine tex
    Chambered with PTG 243AI reamer built specifically for the TUBBS 115 grain bullets. Tight chamber, tight not turn neck.
    Jewell HVR trigger set at 28 ozs
    NF 3.5-15x56 2 DD
    Nightforce 20moa 1 pc base.


    Load:
    Winchester Brass 243 win.
    Federal 210m primers
    115 grain DTAC Moly .585 BC
    2.815 OAL .010 off of the lands.
    48.5 gr. RL25 (46 gr. RL25 fireforming load .5moa or better, good velocity)
    3178 fps.



    Antelope taken at 423 yards with above rifle...

    [​IMG]
     
  11. Warbird782

    Warbird782 Well-Known Member

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    GO with the 8" Twist. I shoot the 105 Bergers extremely well with this. I have not tried any lighter bullets Because I have had such good luck with the 105's.
    Gun: Rem 700 VS, 27" Shilen Selct Match, Leupold 8.5-25.
    Load: Berger 105, 46gr Viht 165, Lapua case, Fed 210M primer.
     
    Last edited: Feb 26, 2008
  12. TOM H

    TOM H Well-Known Member

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    Reason I asked about the twist for the 243AI last year I decided to have a 243AI build so I decide on a Hart 27" 1/10 twist barrel as I plan on shooting 80/87gr bullets. I've got an extra 6RemAI that I've been think of using a 1/8 twist barrel Broughton 5c or Bartlein 5R 1/7.5 twist I was just trying to get some first hand knowledge if I decided to shoot the lighter bullets in a 243AI.
     
  13. mjbine

    mjbine Active Member

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    SM,
    Where can I get the 115 DTAC Molys at? I heard that are disconituned. Or are you putting the moly on yourself?

    Thanks
    Mike
     
  14. Sendero_Man

    Sendero_Man <strong>SPONSOR</strong>

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    I still have about 600 of them....

    I just talked to Tyler at Superior Shooting Systems. (Dave Tubb's company)

    phone is 1-806-323-9488 DavidTubb.com.html


    He said the 115 is still available in the new Boron coating. This is similar to moly, with no erosion problems if you are in a humid area.

    $100 per 500 plus shipping.

    thanks,
    Scott