Featured Rethinking 280AI build

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by willyqbc, Nov 3, 2018.

  1. willyqbc

    willyqbc Member

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    Have all my components and donor rifle on hand for an 8.4 twist .284 cal of some description, built to shoot 168 LRX or possibly 160 accubond. Had been pretty sure it was always going to be a 280AI. Measured up my magazine box and basically came up with a 3.300 COAL to function properly...sunk a 168 LRX into a 280 rem case...and WOW!!!....that beast is sure using up a lot of capacity!! Started looking at cases that are a little shorter as a comparison, just to see what that looks like, and got pretty interested in the ole 284 win.

    This is what 3.300" looks like. the case on the left is a 300 wsm case which is just a hair shorter than a 284 win case, one on the right is a 280 rem case. 160 accubond, 168 LRX

    [​IMG]

    OK, so what kind of performance difference are we lookin at? Using quickload with a 22" barrel (length I want on this rifle), same pressure max, same coal (3.300) etc etc....everything the same except caliber

    65000 PSI

    280 AI - 2932fps 61.9 grns RL26
    284 win - 2916 fps 60.5 grns RL26

    hmmm... was expecting the ackley to have a signifigant advantage....guess not when loading these heavies

    This is the donor, M70 featherweight, Bought it cause I love the grain in the stock! It will be finished with a cerakote my smith has that looks a lot like old school bluing to keep the classic look. The more I think about it, the more I feel like the 284 win has the right "feel" for this rifle.

    [​IMG]

    Any reason you all can think of not to abandon the 280 ai in favor of the 284 win for this build??

    something i'm missing in my thought process??

    Thoughts appreciated
    Chris
     
  2. Plinker147

    Plinker147 Well-Known Member

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    284 won’t reach 280ai velocities in a 22 in barrel. Seat the AI our further passed sammi specs and you will get some gains.

    Both good choices though.
     
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  3. MudRunner2005

    MudRunner2005 Well-Known Member

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    I thought the M70 had a longer magazine box than that...Similar to a Rem 700 @ 3.65"...

    You might need to keep the M70 original and get you a Rem 700 LA donor in .270 or .30-06, and build from there.

    Also, look into the .280 Sherman. It will get you the most performance from a standard bolt face long action cartridge. It will put down numbers similar to the 7mm RemMag. It's basically a .280 AI that's been improved even more. You use .270 Win brass to form for it. I also wouldn't go less than a 26" barrel for optimal performance. You can even use your current 7mm blank you already have for it.

    One last thing, the new Berger 175 Elite Hunters would do exactly what you're asking, but have a MUCH higher BC than the Barnes or Accubond.
     
  4. Slick8

    Slick8 Well-Known Member

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    Stay with the 280AI or better yet the Sherman. I feel it's the most you can get from a standard cartridge.

    Go with a Wyatts extended magazine box. It appears that you're going with a m70 so I'm not sure what they offer but you can get 3.99" in a mod 700.

    If you wanted to go with more modification you could open the bolt and feed rails then chamber in a WSM.
     
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  5. cape cove

    cape cove Well-Known Member

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    Yep that the mag length on the M70. I've got one chambered in 270 Wea mag and 3.300 is the length if you want things to function good. I believe if you go with the M70 standard mag box then the 284 Win would be my choice of the two, but if you could open up the mag box then the 280AI would be great.
     
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  6. willyqbc

    willyqbc Member

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    Hmmm....hadn't considered opening up the mag box...good thought cape cove, will have to chat with my smith about that.

    anyone have any experience as far as how consistant rounds are when the bullet is seated down into the powder column? would seem to me having a decent amount of powder up past the base of the bullet could cause some pretty inconsistant velocities....high SD's....yes/no?

    Not really chasing top velocities with this one, 2700-2800 would be fine, accurate/consistant is more important to me.

    Thanks again for the input
    Chris
     
  7. cape cove

    cape cove Well-Known Member

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    Don't mind slightly compressed loads, but not a fan of heavy compressed loads espically with a stick powder.
     
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  8. can1010

    can1010 Well-Known Member

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    built a 284 win this year and have a 280 if both are loaded to 3.2-3.3 they are basically the same the 280 ai will get a little extra at that length but really shines once you get 3.5.
    284 win with 165 game changers,162 ELD-X RL-26 2910-2922.
    RL-16 and 23 are a bit slower but very stable in my gun
    if you do the 284 win watch what dies you use the SAAMI spec will be overworking your brass in the case web area
     
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  9. Hand Skills

    Hand Skills Well-Known Member

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    I too looked hard at .284 vs .280AI, and can appreciate what you're saying.

    To me the AI makes sense if you can load to ~3.5 OACL, that's doable in a M70, but requires some parts and some work.

    Even at SAAMI length, the extra case capacity of the AI is an advantage - the 160's and up like slower powders, so less case capacity means fewer powder choices or more severe compression in the case.

    Also, I know Barnes does not recommend seating their bullets way out - I don't have any experience with why, but I have read it in their data.

    To me, the biggest attraction to .284 is brass. Easy to neck up Lapua 6.5x284. Coupled with the fact you could throat for ~3.1 OACL and run from your existing mag well, that is certainly the path of least resistance.

    Fewer options for the AI. Some guys form from '06 brass, but the cases come out a few hundredths short. Custom reamers do exist, designed for a 280ai on '06 brass, they're just a bit shorter in the neck.

    I had a pre '64 M70fwt drop into my lap - 25" 1:9 pencil barrel pillar and glass bedded, unfired. I didn't let the fact it was chambered in 280 Rem dissuade me. Even though loading manuals sometimes suggest otherwise, a couple more grains of case capacity (.280rem/.284 vs AI) will yield ~50fps when loaded to equal
    pressures.

    There are a lot of factors to consider, but from a performance standpoint, it will be hard to argue any practical difference.


    Edited to add; I'm too slow a typist - everything has already been said!
     
    Last edited: Nov 3, 2018
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  10. adk hunter

    adk hunter Well-Known Member

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    I would choose the case first then the bullet. Having a certain bullet in mind may not be what your build tells you it likes or loves. I agree with not stuffing the case full with lead or copper. I bought lots of different bullets to compare their dimensions side by side. Intended range of course will play a part. I do like the .284 for that nice walnut! I did a .280 AI on a pre-64 22" and LOVE it. It loves the 150 lrab...
     
  11. benchracer

    benchracer Well-Known Member

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    This is a pic of the magazine in my Model 70 sporter. Note the spacer at the rear of the magazine. The internal mag measures 3.4" to the face of the spacer. Measured to the rear of the mag (behind the spacer), the dimension is 3.6". It would be a simple matter to have a smith remove the spacer. My rifle is in .264 Win Mag, so not sure if the standard rifles are set up this way, or not. Is this what your magazine looks like?

    win70.jpg
     
  12. codyadams

    codyadams Well-Known Member

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    I modified a magazine in a Winchester model 70 chambered in 300 win mag by doing exactly that, took about 30 minutes with a dremmel to get it out, clean it up, and paint it to make it look good. Function was perfect, and allowed the longer OAL. Very, very simple fix to your problem. Stick with the .280 or AI.
     
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  13. TOM H

    TOM H Well-Known Member

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    [​IMG]



    Chris[/QUOTE]






    [​IMG]

    Any reason you all can think of not to abandon the 280 ai in favor of the 284 win for this build??

    something i'm missing in my thought process??

    Thoughts appreciated
    Chris[/QUOTE]

    About 7 yrs ago I decided to have couple rifles redone new stocks/barrels chamber for the 280AI and 284. I had gunsmith order 2 barrel from Lilja same twist /barrel length for them. I had 280AI long throated so could seat out to appr 3.500" and 284 was on long action so could see out to appr 3.300". I had been shooting 6.5x284 Norma and that was build long action also been shooting 280AI before spec 280AI and fireform case, OAL was appr 3.400", couldn't seat out further and that one had Kreiger barrel.

    Being able to seat out 280AI, I could shoot Berger 180gr VLD and shoot some of the newer ones today. It's hunting rifle so don't do much target shooting and I own other hunting rifles so don't hunt with 280AI/284 every year. The 284 I most use 160gr AB, and have pretty good load using 162gr ELD-X with R-26 and 168gr Berger.

    I plan on taking both rifles and use one as back and first year had buck and antelope tag here in Co so used 284 and 280AI on bull elk tag. I've got friend with ranch out eastern Co and got Plains elk tag and used 284 for that tag.

    I went with long barrels so I could take advantage ballistic on both. If your happy with QL then it be flip of coin.
     
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  14. 257Tony

    257Tony Well-Known Member

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    I'd abandon the 168 LRX before I abandoned the 280 AI. That particular bullet is longer than the Berger 195. If you want to shoot Barnes, step down to the 145 LRX, or if it were my rifle I'd shoot the 168 Berger VLD.
     
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