6mm / 243 105 GR A-Max - What Cal?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jrkotz, Dec 9, 2010.

  1. jrkotz

    jrkotz Well-Known Member

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    Hey guys -

    Looking for a new barrel for my LRPV.

    I've decided that the 105 gr A max bullet is the one I'd like to base the build around, main purpose is 600 yd bench shoot and prairie dog shooting from 400-700 yards.

    The question I have floating around in the ol' knoggin is - what brass should I put ehind the bullet?

    Looking for MINIMAL brass work with MAXIMUM speed and accuracy. Goal is to have a few hundred rounds to shoot the long distance dogs that my 223 and 204 can't reach.

    I'd like to scream the thing out at 4000 fps :D

    But seriously, what do you have in mind? Thanks!
     
  2. Catfish

    Catfish Well-Known Member

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    Forget the 4,000 fps with a 105 gr. bullet in .243. I pushing the 107 bergers around 3200 to 3300 fps right now with a 6 -284. You could get alittle more with a 6- 06 and a long barrel but to get to 4,000 fps your looking at a belted mag. case. If you do build one make sure your twist is fast enough to stablize the the heavy bullets.
     

  3. jrkotz

    jrkotz Well-Known Member

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    Big smiley behind "4000 fps" means I know it's a pipe dream.

    I just really want to try to cheat the wind out to 600 or so. It really kicks on the plains of KS, CO and SD. Never seem to have a calm day.

    Is that 6-284 similar to what I could get from a 243 AI?
     
  4. adam32

    adam32 Banned

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    I'm getting 3300 with a .243 AI and 105 Bergers...can hit 3400 if I really want to push the limit...
     
  5. B23

    B23 Well-Known Member

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    I'm pretty sure a 105Amax would turn to dust and never even hit the target if launched out of anything at 4000fps
     
  6. Gene

    Gene Well-Known Member

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    I shoot 500 meter groundhog matches with a 6BR and 6 Dasher (both 8 twist), but neither will get much over 3,300 fps. In fact, about 25% of groundhog match shooters favor this cartridge because of its long range accuracy. The 105 gr. A Max with Lapua brass, RL15 or Varget, is very good. But I prefer Berger, BIB and Sierras in my custom rifles. I do have a factory Cooper 6BR 8 twist that loves the A Max.
     
  7. Trickymissfit

    Trickymissfit Well-Known Member

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    I shoot a 6/250AI with mostly 105 grain AMAX bullets and the big Sierras. It's good for a hair over 3150 fps with H1000 powder and a 26" barrel. 3000fps seems to be the accuracey load for the barrel. Like to know how to get 3300 fps out of the 6/250AI!! And that's with a bigger case.

    I did look at ten targets earlier in the week that had ten bug holes in the bull on each one. The round was a 35 remington case necked down to 6.5, and shortened a little bit. The shoulders looked like 30 degree, and the body was similar in taper to an Ackley. Kinda like a 6.5PPC but on steroids. The gun was an HBR gun so the case held a similar amount of powder to the 30-30
    gary
     
  8. ewallace

    ewallace Well-Known Member

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    I like the 6mm BR for shots to 600 yards and then the 6 Dasher or 6X47 lapua out to 1000 yards
     
  9. Trickymissfit

    Trickymissfit Well-Known Member

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    I honestly think that when talking 500 to 1000 yards, you really need to be thinking about a 6.5 or a 7mm. Nobody wins 1000 yard shoots with a 6mm anything these days (actually nothing new). You want one of those .600+ B/C bullets. At 500 yards a 6mm Berger 88 would be the round to use (assuming the throat and barrel were cut for it) on a windless day. But even then a good 6.5 would be better. If I were shooting a 500 to 1000 yard groundhog shoot, I'd probably go with a 6.5x47, or a 6.5x.284 short (-.125").
    gary
     
  10. jrkotz

    jrkotz Well-Known Member

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    Practically, my thoughts were 243 AI @ around 3300, but I've been getting recommendations for 6mm and 6mm AI and 6x47L.
     
  11. screech

    screech Well-Known Member

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    If your stuck on the 105gr. amax Id check into a 6catbird or 6mm-06 improved of some sort. If your going to just be dusting dogs mostly check out the 87gr. vmax, If youwanting something with less case forming, do a singe shot a 6mmAI or if you want a repeater run a 243AI
     
  12. James H

    James H Well-Known Member

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    Gary,
    I think you will find that you are mistaken. Most Light Gun matches at Byers, CO (1000yd IBS)were won this year by a 6mm. I managed to win group on 2 relays this year at the IBS 1000yd Nationals, one was with a 6mm 105 A-Max, I know that there were others who won relays at the Nationals with 6's too. The wind was pretty rough at the Nationals this year and usually is unforgiving at Byers too.
    The 6mm Dasher dominates at the Deep Creek range at Missoula, MT.
    The Original Pennsylvania 1000 Yard Benchrest Club, Inc. The Birthplace of Long Range Shooting.
    Switch the drop box on the left from Pennsylvania to Montana and check results.

    Since this is a Long Range hunting site I will add that I think the 6mm may be a little inadequate for shooting big game at 1000yds though.

    James
     
  13. jrkotz

    jrkotz Well-Known Member

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    Are you talking 6mm BR or 6mm Remington? I assume BR.

    I'm not intending this for big game - Just prairie dogs and paper.

    ** And not a LOT of prairie dogs either, most are shot up to 400 YDS with my 204 or 223, this is for the occasional longer range poke.
     
  14. James H

    James H Well-Known Member

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    jr,
    My general 6mm comments were just in reference to the .243 cal bullet and not a specific cartridge. The 6mm cartridges that I have seen do well at 1000 yards are the 6mm Dasher, 6 x 47 Lapua, and the 6mm Creedmoor. I have been shooting the 6mm Creedmoor, pushing the 105 A-Max 3170 fps but think it is a little hard on barrels for target shooting so this year I will switch to either a 6 BR or Dasher, most likely the Dasher. The Dasher will typically give 3000+ rounds match winning accuracy before dropping off. By the way the 6mm Creedmoor is just the 6.5 Creedmoor necked down to 6mm with no other changes. It has the exact same case capacity as the .243 Win, but the Creedmoor is a little shorter and has a little longer neck.
    Hope this helps.

    James