.243ai

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 7mmSendaro, Nov 22, 2007.

  1. 7mmSendaro

    7mmSendaro Well-Known Member

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    My Dad is considering buying a CZ 550 in .243 Win, then rechambering to .243AI. Two questions:

    1) What is the best way to form brass? I have seen reference both to fire forming .243 win brass and sizing down from 30-06 brass.

    2) How much barrel length is required to get good performance from the extra case capacity?

    Thanks,

    Brian
     
  2. TMR

    TMR Well-Known Member

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    Mar 26, 2006
    The easiest way to fireform is to just use 243 brass. We use H380 and a 100gr bullet seated to the lands. Forms cases perfectly and is extremely accurate as well. We always have a 100 fireform loads ready to go when we go shoot prairie dogs or chucks. It makes the forming process go a little faster and more fun:D.

    Out of the 6 243AI's we have here are the avg. velocities:

    22" Factory Barrel: 70 gr BT's @ 3850fps
    26" Krieger: 105gr Bergers @ 3230fps
    26" Lilja: 105gr Bergers @ 3247fps
    27" Lilja: 105gr Bergers @ 3275 fps
    28" Lilja: 105gr Bergers @ 3317 fps
    28" Kreiger: 105gr Bergers @ 3310fps

    All of the 105gr loads are using the same charge of RE-22. All but the factory barrel are 1-8 twist.

    It all depends on what you want to use the rifle for. With the factory barrel (1-10 twist), you can probably stabilize up to a 95gr Berger depending on what elevation you are. We have shot the 87gr V-Max at just over 3800fps with the 28" barrel rifles. The Lilja is a 3 groove, and it pretty much destroys the bullets. Half of them don't make it to the target and the other half aren't real accurate. The Kreiger shoots them just fine. I have a Broughton that should be here next week to test against these barrels. I will post info on that when I get her finished up. We my other broughton barrels, they seem to be 70-100 fps more than the Lilja's we normally run. Accuracy is even with both barrels. Since it will be a coyote/tactical rig, I wanted to see if I could get the same velocity with a little shorter barrel.

    This is a very accurate little cartridge that is not finicky at all. Brass life is good. We had one barrel with almost 1700 rounds through it and was still shooting tiny groups at 100. We replaced it with a faster twist.

    Oh, and it does a number on deer and antelope with the Berger. I have shot antelope out to 580 yds and they instantly are on the ground.

    Hopefully I have answered some of your questions.
    Travis
     

  3. adam32

    adam32 Banned

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    Nov 14, 2007
    Thats good to know Travis. I am having a .243 AI built for me right now, it will have a 1/8 twist Broughton 5C barrel. I would like to know how many grains you are running in those loads? Be sure to keep us posted on that Broughton and how you like it, I still have time to switch to another barrel if they aren't that good...

    Thanks :cool:
     
  4. TMR

    TMR Well-Known Member

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    Adam,

    We use 49.0 grs of RE-22 and seat to just touch the lands. I have no doubt the Broughton will shoot great. My 7mm STW with a broughton gets a solid 100fps over my Dad's Lilja with the same load and barrel length. They both shoot 1 hole groups, but I do get more velocity. I will make a post when I get the rifle done.
     
  5. grit

    grit Well-Known Member

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    I own a CZ 550 in 243win. I've considered the same thing. Souds like a good idea. What does a rechamber cost? How do you make and size cases?
     
    Last edited: Nov 23, 2007
  6. TMR

    TMR Well-Known Member

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    555
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    Mar 26, 2006
    Not sure what a rechamber runs....To make cases, just fire standard 243 ammo in the ackley chamber...Redding makes 243AI dies to reload with.
     
  7. 257speed

    257speed Well-Known Member

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    Getting your rifle rechambered can vary a little. If you have open sights that have be lined up again (indexed) it costs slightly more, but generally to make a standard cartridge into an improved, runs anywhere from $100 to $175.