6mm-284vs 6mmAI

Discussion in 'Long Range Hunting & Shooting' started by Bkknupp, Feb 12, 2014.

  1. Bkknupp

    Bkknupp Well-Known Member

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    Anyone have any pros and cons on either of these two rounds? I wanted to do one of these two for deer fun gun.
     
  2. mustang58

    mustang58 Well-Known Member

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    The 6mm AI doesn't gain much over the 6mm. There is a list of the % improvement over the parent cartridge for all cartridges that Ackley improved. Check it out. I have a list but don't know how to attach it here. I'll bet it is on the net. Therefore I would go with the 6x284.
     

  3. AZShooter

    AZShooter Well-Known Member

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    I would think the 6mmAI will have a longer barrel life for two reasons: less powder longer neck.

    While you have to neck down either 284 win or 6.5-284 (my choice) to get a 6mm-284 you have to fireform the 6mmAI.

    A more pertinent question might be which brass is readily available? Same for dies.

    To my knowledge only Rem and Win make 6mm Rem brass. You could buy RWS or Norma 7 x 57 brass.

    The 6mm-284 can use win, norma or Lapua brass.
     
  4. Bob the nailer

    Bob the nailer Well-Known Member

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    I shoot a 6mm-284, 12 twist. All I can say is Wow is that thing flat shooting with very minimal recoil! I zero at 100 yards and it prints +2.5" at 200 yards then zeros again at 300 yards. I reshot this at the ranges just because I was amazed at the results.

    I would build a 6mm-284, easy cases to obtain, no fire forming, simple necking down and accurate.
     
  5. AZShooter

    AZShooter Well-Known Member

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    I might as well admit I have THREE 6mm-284s. I began with a monster 20 lb heavy barreled rig twisted to shoot 115s. Ended up with 105 hybrids at 3445 fps.

    I owned the reamer and an old lathe. Decided to chamber and fit a 20" 243 rem takeoff to a Ruger M77, my first barrel job. That rifle shoots the 87 hornady at 3375 fps

    Then rechambered a 24" 243 on a SA Rem 700. It shoots the 95 gr Berger classic at 3350 fps.

    Those sporters are flat shooting: Ruger with 87 gr 1" at 100 4.6 low at 300
    Win with 95 .9 at 100 4.7 low at 300

    Must admit I love this chambering....
     
  6. longrangebo

    longrangebo Well-Known Member

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    I went to my smith with the same question, He talked me into a 6 AI even though the 6.5 284 brass is better, I am glad he changed my mind! I run 52 gr. rel 19 with the 87gr. hor. honest 3660 no preasure at all. Even though I turn the necks to make them the same I can shoot factory ammo to get cases neck is .270 I use win. brass I do have a 28 inch barrel, also a brake so I can see my own hits
     
  7. longrangebo

    longrangebo Well-Known Member

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    Forgot to mention, Richard Franklin, had a good write up about them on the 6BR fourm that is where I got my starting loads from. He was on the guns of the week!
     
  8. Outlaw6.0

    Outlaw6.0 Well-Known Member

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    I really don't think there is a wrong choice here, each has their own pros & cons. I own both of these chamberings & have passion for both.

    I'm not sure why someone would say you can't get much improvement out of the 6mm case, all you have to do is look at it to tell that ain't the case. It's generous taper & gentle shoulder SCREAMS for improvement. As mentioned before, it's long neck coupled with a lesser case capacity should provide more bore life than the x284. Obtaining cases can be a PITA, the one true caveat to this cartridge. Getting that case to properly feed is a problem I encountered as well. Accuracy has been very good with flatbase bullets in the 85-90grn range as my rig is a 1-12".... the only true regret I have. Velocity with great case life is in the 3450-3500 range with this bullet weight & Rem brass. Fireforming is a pain but is still quite accurate as a plinking load.

    The 6x284 is an outstanding cartridge, very few can do what the x284 does as easily as it does it. Lapua brass, run it though the sizing die & be done with it (I step mine down in 2 stages). According to Sierra, the x284 set a world 1000yd benchrest accuracy record... that says all it needs to say about it's accuracy potential. Mine shoot in the .3's routinely. Feeding the x284 case also has it's issues as outined by gun gurus such as Kirby Allen. I run mine though a HS performance centerfeed DMB, it isn't butter smooth but it does feed reliably. Velocity of the x284 should & will beat the AI all day every day (with pressures being equal). 107's in the 3500' realm is something to behold, no recoil & lazer flat trajectory; what else can you ask for? Bore life is a concern to some as any overbore uber velocity magnum WILL torch your bore if you treat it like a 223. Keep'er cool & keep pressure on the SANE end of the spectrum, I bet you'll be surprised how long it will last you.

    I personally think the AI is the sexier looking cartridge of the 2; outside of that, flip a quarter & run with it.

    You can't possibly lose here.



    t
     
  9. MontanaRifleman

    MontanaRifleman Well-Known Member

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    The 6-284 for Lapua brass.
     
  10. Bob the nailer

    Bob the nailer Well-Known Member

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    Off topic, I liked my 6-284 so much I built up a 22-284 :) and so far just love that thing :D
     
  11. Booney

    Booney Well-Known Member

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    Go with the AI it's got a sweet performance to barrel life ratio! The 284 has great performance but the barrel life is about half of the AI.
     
  12. Bkknupp

    Bkknupp Well-Known Member

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    I've about decided to go with the 6-284 mainly because of the availability of brass.
     
  13. Picketpin

    Picketpin Member

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    The 6mm AI is essentially perfectly bore balanced. You will get the best over all accuracy and load densities with it. The increase in case capacity is minuscule and really doesn't gain you much. EXCEPT like the 22-250 AI the straight walled case and the sharp shoulder prevent a lot of case stretching and your brass last a lot longer. THAT said how many times are you actually going to shoot it at deer. If you buy a 100 cases they will last a life time of big game hunting.

    The only reason I would make the 6mm AI is if I were going to use it as a varmint rife and shoot it a lot. Then brass life becomes an issue.

    The 6-284 is essentially the same case capacity as a 6mm-06, the data is interchangeable. If the 6mm Remington is nearly perfectly bore balanced and the 6mm AI IS bore balanced . Then the 6mm-284 has to be overbore by definition. Basically your talking the 7x57 case versus the 30-06 case. The 6-284 is a pretty modern case style, straight walled and sharp shouldered with a rebated rim. Not much to improve in terms of case design.

    The AI is a more versatile case for most applications. You can shoot the light bullets at varmints and the 95-105s at deer/antelope.

    There is an UP side to the 6-284. You can drive heavy for caliber bullets significantly faster than you can with the AI. That does come at a cost of more recoil, noise, and cost but as a hunting rifle just how many rounds are you going to actually shoot?

    The DOWN side is while you can shoot varmint weight bullets 70s etc because the 6-284 is overbore it requires MORE powder to generate the same pressures and velocities as the 6mm Rem or the 6mm AI.

    I own at least 5 rifles in 6mm Rem. I have nevr built a 6mm AI because I just don't see it worth the cost. Of course mine are used as dual purpose rifles to shoot rockchucks and deer/antelope. I have several 22-250AIs, because I DO use them for varmints and brass life is a real issue when firing thousands of rounds a year. I own several 257Roberts AIs because they ive me damned near 25-06 velocities with 110-120s with less powder and recoil. Again if the 257 Roberts or AI on the 7x57 case is bore balanced aand it is, then the 25-06 is over bore and does best with heavy for caliber bullets.

    Now to the 6-284. I bought my first one in 1972. Somebody had wildcatted a Flat Bolt Ruger 77 and the store sold it to me priced right with brass and dies. It is/was my favorite antelope cartridge for years and along the way I have built 3 more on the Ruger #1 to get advantage of the longer barrels. These are HUNTING rifles designed to shoot deer/antelope and the occassional long range coyote with HEAVY bullets. I finally built a fast twist 1:8 twist Shilen barreled #1 to shoot really heavy.long VLDs at rockchucks sitting a LONG ways of.

    Either can be made by simply rechambering an existing 243 or 6mm unless you want to shoot VLDs then you'll need a new, faster twist barrel. The advent/popularity of the 6.5-284 and great Lapua brass doesn't hurt.

    I'd just decide exactly what you are going to do with the rifle and what YOU are doing it for.

    Closest to a 6mm AI I have is a custom #1 in 22-6mm AI with a 1:7 twist barrel to shoot heavy VLDs in .224 caliber.

    Ross
     
  14. marioq

    marioq Well-Known Member

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    so I bought a barrel in 6x284 thinking it was a 6.5. Also have dies. I have a bunch of 6.5x284 lap brass. Can I just resize this in the dies??? I have not built it yet so I have to get my new action and then I am game....
    Just curious as I know nothing about this cartridge.

    Thanks
    Mario