to ackley or not

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by buckyne, Dec 24, 2011.

  1. buckyne

    buckyne Active Member

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    I have a ruger 280 that I am happy with as a deer rifle.

    I am thinking about rebarreling with a custom barrela and contemplating changing to a 280 ackley at the same time. I am confused though as there are two versions. The Nosler Ackley and the older original. I have plenty of brass for the 280 so fireforming in the older ackley seems the way to go. But is there a benefit to the nosler version other than the available nosler ammo and brass? Can you fire fireform 280 ammo in the nosler version?

    Any thoughts/ feeback would be appreciated.
     
  2. Fiftydriver

    Fiftydriver Official LRH Sponsor

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    I would personally go with the old true Ackley Improved as it will be easier to get dies for in most cases. I am not a huge fan of Nosler brass. IN my opinion, way over priced for what you get so I would just form your own brass. For this type of rifle 50 rounds of formed brass would be plenty, I would never form more then 100 rounds for a long range rifle, no need.

    Performance wise, you will be right at factory loaded 7mm Rem Mag performance levels. Many say that the 280 AI will fully match the 7mm Rem Mag. This is not true. This is because a properly loaded 7mm Rem Mag will easily match a 7mm Weatherby Mag which is generally loaded a full 100 fps over the Rem Mag, why, I have no idea as the Rem Mag actually has slightly more case capacity. You just have to be careful when working up loads, NEVER USE 7mm WBY data in a 7mm REM Mag.

    Back to the 280 AI. Loaded safely, it will come very close to matching "FACTORY" 7mm Rem Mag ammo specs and do so with around 8-10 grains less powder. It truely is a great chambering as long as you go into with realistic expectations. Shoots very accurately, even fireforming loads generally shoot quite well. Long barrel life, great performance on big game. Probably one of the very best chamberings based on the '06 parent case.
     
  3. woods

    woods Well-Known Member

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    Great advice from Kirby, as usual. I have a TRUE 280AI and made the mistake of trying Nosler 280AI brass before I learned the difference. No real harm done, just severely flattened primers.

    Now I use 280 Rem brass and have no problem. Nosler makes good 280 Rem brass, at least the box that I got. I have had less than good brass in other calibers from Nosler though. Most of the time (or all of the time for me) you will want to fireform the case before working up your best hunting loads anyway.

    I shoot the 160 gr Accubond and get just over 3000 fps safely and consistant accuracy, which is just perfect for me.

    Like Kirby says, the fireforming load can be accurate and operate at 280 Rem velocities (as long as you don't try it with a false shoulder)

    [​IMG]
     
  4. Fiftydriver

    Fiftydriver Official LRH Sponsor

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    Just a bit more to add, when an AI chambering is set up properly, the virgin brass should have a slight (roughly 0.004-0.005") crush fit in the chamber. This means that the shoulder of the case where the shoulder/neck junction is will be crushed slightly when the virgin brass is chambered. This is critical, unfortunately, many AI rifles are not set up properly.

    You should be able to feel the crush fit of the brass when fireforming with just a bit of resistance on the bolt when you lock it down.

    This crush fit does a couple things, first, by design, its intended to hold the case solidly back againt the bolt face. This aids in good powder ignition which helps fireforming and improved round, it also nearly eliminates case wall stretching and thinning ahead of the solid case head and will prevent case head seperation. This is very important.

    This also helps center the fireforming round in the chamber properly which aids in accuracy. This is why a properly set up AI rifle will generally shoot ffireforming loads very well, often times into that 1/2 moa group class.

    On the Nosler brass that you were getting flattened primers, this was a headspace issue that was causing the flattened primers. If you want to use the Nosler brass, you should at minimum set the chamber up to headspace properly on this cases shoulder. IF your getting primer flattening, likely you also got some case stretching as well. May be very mild but may also be worth looking into. A case head seperation is not a fun thing at best and can be very serious at worse.
     
  5. dragman

    dragman Well-Known Member

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    the ackley cartrages are very nice! P.O. ackley was the man!
     
  6. panama

    panama Active Member

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    +1 on that kerby, it really does what you stated, even fireforming it. my wifes first antelope died at 378 yrds. 139 horn. @ 3200fps.
     
  7. panama

    panama Active Member

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    right again,the only thing i do differntly is use 10-11 gr. of uniqe fill the case to within 1/16 and plug with wax or bar soap. load in the chamber,except in a mauser slip under the extractor then chamber it, blows the case out perfectly every single time have never lost a case,BTW use only large pistol primers.my .2% hope this helps.
     
    Last edited: Dec 25, 2011
  8. panama

    panama Active Member

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    sorry, i had left out what to fill the case with in my previous entry, it does absolutly no harm whatsoever to the chamber throat or rifling, and is not a false shoulder.
     
  9. Sennaspeed

    Sennaspeed Well-Known Member

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    Since the Nosler version is the only one standardized by SAAMI the die manufacturers are reaming their new 280AI dies with the Nosler chamber.

    Like all "wildcats" (I know, improved cartridges are not considered wildcats) the dimensions of an Ackley 280AI chamber may vary greatly. The SAAMI standard has fixed those dimensions and provided a tolerance range.

    I use Nosler brass and as per usual I form a false shoulder to headspace tightly against for the initial loading. I like to feel my headspace.

    After the FF stage I use the great Lee Collet Die to neck size my brass. I'll run the cases through a Redding body die or FL die when the chambering gets too tight.

    Fact is that the 280AI is one of the finest of the AI cartridges and the performance improvement over the parent round is far greater than is typical with AI's because the standard 280 is limited by SAAMI to an anemic 60k PSI MAP while the 280AI has a 65K MAP. The capacity advantage remains but the MAP allows 5k more pressure on top of that capacity.

    Finally, I know that the regular 280 could be loaded to 65K but you'd be on your own because there is no tested, published data for the 280 which approach 65k.
     
  10. Sennaspeed

    Sennaspeed Well-Known Member

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    What constitutes a "properly loaded" 7RM?

    The SAAMI MAP for the 7RM is 61k PSI while the MAP of the 7Wby is a full 65k. The 7RM can match the 7Wby only by exceeding SAAMI MAP. SAAMI cites unexplained pressure spikes with the 7RM case and therefore lowered their MAP to stay on the safe side when these spikes occur. (the 243W suffers the same malady and the same solution was utilized.

    When all are loaded to their SAAMI MAP the 280AI will be right at 7RM velocities and the 7Wby will be the fastest.

    I'm pushing the 162gr Amax to a consistent 3050fps using 64gr of Magpro in a 26" barrel. The 168VLD exits at 2990-3000 using the same load. Both Magpro loads are one grain under max (per Johan Loubser, ballistician at Accurate Powder) and QL shows pressure to be below the MAP but given my high velocity I'm calling both loads maximum even though I'm experiencing zero pressure signs.

    Keep up the great work Fifty, I enjoy reading your responses.
     
  11. Derek M.

    Derek M. Well-Known Member

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    "Not"
     
  12. Fiftydriver

    Fiftydriver Official LRH Sponsor

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    Sennaspeed,

    I do not wish to take this thread off topic but please tell me what allows the 7mm Wby to safely be loaded to 65K pressure but makes the 7mm Rem Mag to be unsafe to be loaded to this same pressure level???

    Just because the factory downloads the 7mm Rem Mag to make their other 7mm magnums look more impressive is not a good reason to underload the Rem Mag.

    This is why they can make it seem that the smaller WSMs can match the standard belted magnum case performance which is simply laughable when both are loaded to their full, SAFE potential.

    The 7mm Rem Mag brass is EVERY bit as strong as the Wby if not stronger, has slightly more case capacity and rifles its chambered in are every bit as strong as any rifle chambered for the Wby. Why would you let the industry tell you which is the higher performing round when their specs are based on very little to do with what each round can actually do in reality.

    No flame or disrespect of any kind intended, just would like to know why you think the 7mm Rem Mag can not be loaded to the same pressure as the Wby?
     
  13. panama

    panama Active Member

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    I had posted previously that my wife 139.gr.horn. @ 3200fps. was driven by only 62.gr load. also in fire forming 10-11 gr. of said powder was good for 243 thru 30-06 cases, for most belted cases it takes 14.gr. and a lrg. pistol primer to fire form completly. built my first 30-06 AI in 89,tried to fire form with a 110 gr.sra. load was 6o.gr.4350imr case never formed completly had a radius at the shoulder like a wby not the nice sharp 40 AI. and the case was foreshortend which could be a dangerous thing as head space had changed since that time i have used the corn meal or grits method way waste those $$ components (,bullets) cornmeal is way less and it does the job very well.again just my .2%
     
  14. Sennaspeed

    Sennaspeed Well-Known Member

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    I completely agree that the 7RM case is every bit as strong as the Wby and should by all rights be capable of handling 65k but ballistics labs have noted unexplained pressure spikes in the 7RM since it's intro in 1962.
    After many of these reports SAAMI took note and concluded that a pressure reduction was in order to compensate for these pressure spikes.
    Since the publishers of loading manuals are reluctant to publish loads which exceed SAAMI MAP (the standard used by the industry) the loads for the 7RM reflect that lower limit.
    Loading the 7RM to 65k means exceeding the latest data whilst not exceeding 65k. How is that pressure determined absent proper equipment?
    At the same time you run the risk of exceeding safe and sane pressures should you experience one of those anomalous pressure spikes which seem to be peculiar to the 7RM and the 243 W.