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Thoughts on Ackley Improved cartrages

Discussion in 'Rifle Country' started by Kachok, Feb 6, 2012.

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  1. Kachok

    Kachok Member

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    This is one thing that has intrested me for a while now, but I have never tried it one, what are your oppinions on AI cartrages, are they really better then the original versions of their respective cases.
    Here are the claimed benafits of AI cartrages
    Slightly improved case volume. Improved speeds as a result
    Better combustion properties as a result of the sharp shoulder. Often claimed to improve accuracy.
    Less case stretch for handloaders, longer case life as a result.
    Are these all true, and if the AI versions can do all of this without any downsides why are they not factory chamberd (other then the 280 AI)

    For those that don't know what I am talking about, an AI cartrage has had it's shoulder blown out to a 40 degree angle instead of the normal 17 degree found on the 06 based cases and 20 degree on the 308 based cases.
     
  2. Mike1234567

    Mike1234567 member

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    Added to my subscriptions...
     
  3. LoonWulf

    LoonWulf Member

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    dont forget less bolt thrust as the cartridge tends to grab the chamber walls harder since there is little to no taper. Ive hear that to be one of the reasons people end up with super high pressure when working with AI style cartridges, they dont get a sticky bolt LOL. Anyway, i still havent gotten my hands on one yet, if been thinking about doing a .30 gibbs in my 1903, and a 260 AI on my savage .243 when its barrel dies.
     
  4. Kachok

    Kachok Member

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    I am dreaming up a 25-06 AI or 6.5-06AI build on a Savage action. Super flat trajectory, moderate recoil and can form from common brass.
     
  5. Gordon

    Gordon Member

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    I believe most Ackley Cartridges used a 30 degree shoulder. Most Ackley cartridges are fireformable with factory ammo, hence "Improved" . The Gibbs not so, I was very disappointed that .270 and .30 Gibbs you could NOT safely fire form factory ammo so that was the deal breaker. 40 degree shoulders are pretty extreme and only used on some wildcats I think.
     
  6. Hocka Louis

    Hocka Louis Member

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    .30-06 AI is my .308 Magnum.
     
  7. Kachok

    Kachok Member

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    No all AI cartrages are 40 degree. All of them I have ever seen anyway.
     
  8. Gordon

    Gordon Member

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    Actually yes some, maybe most are 40 and prolly the ones you are interested in, but Parker came to settle on 30-35 degrees as being "better" in his later years and mine have that angle.
     
  9. Kachok

    Kachok Member

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    Mabey the 35 degree shoulders are better, but whenever I look up the specs on any AI cartrage it is always listed as a 40 degree. That has always been their trademark.
     
  10. helotaxi

    helotaxi Member

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    Some have feeding issues. Not the best suited to semi-autos as a result. There are plenty of newer cartridges built on the improved model such as the SAUMs, WSMs and RUMs as well as the .204 Ruger.

    Not all AI cartridges are a marked improvement in ballistic performance. The .243 is a perfect example. There are still plenty of .243AIs out there. Most guys cite the lack of case stretch as the reason.

    Others provide a significant improvement over the standard cartridge. These are usually cartridges with a lot of case taper and/or a very shallow shoulder. The .257 Roberts and 22-250 are excellent examples of this.
     
  11. Kachok

    Kachok Member

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    Who said the 243 AI was not higher performance then the regular 243? All information I can find on it show it runs neck and neck with the 6mm rem, about 100fps increase across the board. Never did load development on one but that is what I read. I would not expect a 40 degree shoulder to feed as smoothly as a 17 degree in a semi auto. In bolt guns it is not likley to make a notable difference.
     
  12. 35 Whelen

    35 Whelen Member

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    I own a 257 AI and like all the original AI cartridges, it has a 40° shoulder. It netted 200 -250 fps over the standard 257 Roberts, but then again the 257 Roberts is loaded to WAY low pressures(45,000 CUP) for some reason.
    John Barsness of Handloader magazine claims improved cartridges really don't gain you that much performance. Realistically, I'd say blowing out a .308 based, *X57 or an '06 case would gain you 100 fps, maybe a touch more. Can't comment on the other stuff but it sounds like someone rationalizing an AI chambering which is certainly OK!

    35W
     
  13. Kachok

    Kachok Member

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    100fps seems to be the going rate, 280 AI maxes out a 150gr pill 100fps faster then the 280 Rem, the 30-06 AI can push a 180gr 100fps faster then a regular 06, though the difference grows a bit more with 200-220gr bullets. The 25-06 AI is the only one that seems to bump it up a little further in the 150-200fps range, but that might just be because people who tweek that round seem to like 26" tubes.
    It is worth mentioning that the 280AI pushes very close to 7mm rem mag performance in a smaller package burning several grains less powder, and the 25-06 AI matches the 257 WBY with alot less powder (about 8-10gr avarage)
     
  14. 35 Whelen

    35 Whelen Member

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    Funny you mention that. I have an old Ruger 77 that was a 7x57 that Dad had rechambered to 280 Remington. For nigh on 15 years I've only fired two loads out of it; a 140 gr. Partition at a shade over 3000 fps, or about par, and a 160 gr. Partition at a (small) shade UNDER 3000 fps. Don't ask me how...I just owkred up the load and stopped when groups were 1" or less and velocity was acceptable.

    35W
     
  15. Kachok

    Kachok Member

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    That is a bit over the published max load for a 280 rem, the AI maxes out a 160gr at about 3050 fps, every bit as fast as the 7mm WSM that would make for one very dead elk for sure. I don't have any elk down here, so I am looking to make a super flat shooting deer rifle, that is why I am looking into the 25-06AI or 6.5-06AI both should push a 115-120gr bullet to around 3400fps with a custom 26" barrel.
     
  16. nastynatesfish

    nastynatesfish Member

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    i have a buddy that has a 2506ai and has had nothing but grief with it. from loading to spit necks with new brass. dont know what he ever got figured out with it. im still waiting on a 7mm ai mag to show up.
     
  17. Kachok

    Kachok Member

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    Some calibers seem to take to AI very well and others do not. You see alot of 25-06AI and 280AI but how many 270 AI rifles have you seen.......me neither. Never seen a 300 WM AI or 7mm RM AI either. I would think you could make one easy enough. Can you machine a factory barrel to make an AI or would you have to get an aftermarket barrel?
     
  18. Cemetery21

    Cemetery21 Member

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    223AI feeds fine in ARs I have 3 that get quite a bit of mileage on prairie dog trips and feed as well as 223s. I went to AI for just a little more speed and less trimming. I'm just 3 years/loading cycles into it, so not sure how long they will go before trimming. They actually get shorter on fireforming because the taper and shoulders are blown out.

    Edit to answer - mine were cut on 223 chambers. All are custom built from match barrel blanks, but two were shot as 223 before they were reamed out to AI. 223 headspaces correctly in the AI chambers. You lose a little speed in fireforming, but in my case, the accuracy was still there so I could hunt and fireform at the same time.
     
    Last edited: Feb 6, 2012
  19. Clark

    Clark Member

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    223 is SAAMI registered at 55kpsi, so all the published loads and all the commercial ammo is wimpy.

    The case head is good for 75kpsi with long brass life.

    The real advantage of Ackley Improved in 223 is almost not measurable, but important gains are from higher pressure.

    The 270 is registered at 65kpsi and the case head is good for 67kpsi with long brass life. You will never hear of anyone claiming more velocity with 270 Ackley improved.

    I can get 3900 fps with 75 gr in 257 Roberts Ackley Improved, but I can only get 3600 with long brass life.

    There is a sucker born every day, and out of control variables are often the key.
     
  20. Kachok

    Kachok Member

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    I don't know if I quite agree with that, some magnums have a lower max chamber pressure then their standard counterpart, but they are still faster because they can use more of a slower burning powder. Lower peak pressure, but maintains good pressure through more of the barrel. If it were all about peak pressure case volume would mean almost nothing.
     
  21. hang fire

    hang fire Member

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    Decades ago I had a .257 Ackley improved, it was a great deer slayer.

    I also had a .35 Gibbs which was a good moose thumper, but when sighting in that light rifle, I thought it tried to kill on both ends.
     
  22. Clark

    Clark Member

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    223 Ackley at 55kpsi will push a 40 gr bullet 50 fps faster than 223 at 55kpsi.
    223 Rem at 75kpsi will push a 40 gr 300 fps faster than 223 Rem at 55kpsi.
    223 Ackley at 75kpsi will push a 40 gr 350 fps faster than 223 Rem at 55kpsi.

    Conflation occurs when the identities of two or more individuals, concepts, or places, sharing some characteristics of one another, become confused until there seems to be only a single identity — the differences appear to become lost.

    Case capacity increase from Ackley improving a chamber would be an independent variable.
    Velocity would be a dependent variable.
    Peak pressure would be another independent variable.
    If we measure the effect of case capacity increase on velocity, but do not control [have unknown change in] peak pressure, then we have an out of control variable.

    Out of control variables have been associated with bad science, cheating, and having a screw loose.
     
  23. Cosmoline

    Cosmoline Member

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    AI's are a great way of getting a little more power out of a rifle you already have. In the good old days, folks didn't have the kind of spending money (or credit cards) we take for granted now. So ditching your .30-30 for a .308 wasn't always an option. Plus the selection was far more limited. The AI's are a simple, cost-effective upgrade that can be done by a smith quickly. You don't change brass or bullets, you just fire form (at least with the ones I'm aware of).

    Nowadays though people wanting to upgrade are more likely to ditch the old rifle and buy a new one. The AI's are the province of handloading nuts ;-)
     
  24. Kachok

    Kachok Member

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    Well I am one of those handloading nuts :) So they should be right up my alley. I want a long range shooter, something with a little more speed to use where my 6.5x55 would fall off trajectory wise. 25-06AI can push scarry speeds with really good trajectorys, it has "enough" downrange energy but not much more. 6.5-06AI can use everything fron light 120gr bullets at similar speeds and ultra high BC 140gr VLDs at just over 3k to resist wind drift and hit hard 500 yards out. 280 AI is a well known Ackley it is not quite as good at light projectiles but can sling 160-168gr bullets around 3kfps giving it best in class downrange energy, probably more power then I need but I would love to have one anyway.
     
  25. Kachok

    Kachok Member

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    Just bought a Savage 110 (30-06) to be a parent action, looking into barrel options to try a wildcat. Of course if it ends up shooting as well as my mkII I will have a hard time taking the 06 barrel off :D
     
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