Why Is My .280 AI so slow?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Snowfighter, Jun 12, 2012.

  1. Snowfighter

    Snowfighter Well-Known Member

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    So I have tried everything. I have a custom .280AI. Have been trying to develop a load for several weeks now. Have tried 11 or 12 powders. Seat depth. the list goes on and on.
    Found where the high pressure mark lies with my action. Worked slowly back from there to a tight group. She will shoot clover leaf patterns all day if I dont mind 2,500 fps. 162 gr. A-Max. Tried the Berger bullets. They wouldnt group either.
    Whats going on?
    Anybody got ideas.
    Thanks
     
  2. Derek M.

    Derek M. Well-Known Member

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    You sure your chronograph is working?

    What are all of the components and powder charge that are giving you that velocity?
     

  3. cowboy

    cowboy Well-Known Member

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    What length of barrel as well as the components? Run your velocity/data and shoot it at say500 yds and see if your 2500 fps is correct. I've seen quite a few of lying chronographs that should have been shot.

    Any chance you know someone else with a crony? Set them up back to back and see what you get.
     
  4. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Sounds like your barrel doen't like that bullet weight. I had an '06 once that would only do 2600 fps with a 165, but would do 2900 with a 150 or 2600 with a 200. If you don't have a broken chrono, change your bullet weight as your rifle doesn't like it. Most times it is only accuracy that suffers, but velocity can too. What about primers, have you tried more than one make of primer??
     
  5. Rem700

    Rem700 Well-Known Member

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    What powders are you using? My 280AI loved 168 gr Bergers with varget, it would shoot under .2". Right now i'm using 140gr Barnes with again, varget. But it opened up the group size to .35". Still nice for deer at close range with little meat loss.

    Are you using a manual powder dispenser or electric?
     
  6. Snowfighter

    Snowfighter Well-Known Member

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    I appreciate the following.
    I'm shooting a 26" kreiger barrel.
    56.5 gr imr 7828 ssc.
    162 a max.
    I loaded close to max in the book. Backed out a few primers.
    Realized my head spacing was wrong. Started fire forming my brass and only neck sizing. Tuned them down about a grain and a half. Still wouldn't group. Turned them down more till I got the clover leaf I was looking for.
    The cronigraph data was gathered from 3 different cronographs.
    I think the head spacing played part in the high pressure signs. Might try some warmer loads. I'm not sure what to do. If I go to a lighter bullet I will loose bc. Less range.
     
  7. Snowfighter

    Snowfighter Well-Known Member

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    I hand trickle each charge.
    Calibrate my scale each time before loading.
     
  8. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Have you looked at different bullets at all??? I've got rifles all over the map when it comes to bullet make. -- looking back I see you tried Berger.
    I've had tipped bullets want to run slow; heck my tikka 270 is shooting a 130 interbond at 2700 fps with a compressed charge of wc872(50 cal powder) because I got the bullets really cheap and I have hundreds to shoot. The same rifle shoots 130 sierra's to 3000 fps with rl22 and 150's to 2850 with 7828. Another 270 will toss the 130 gmx to 3100 fps-- it's tipped.
    Heck I'm playing with the 171 Barnes matchburner in my 7stw right now and it will do .55" at 2750 fps, but if I stomp it to 3100 fps, the groups hit 2" or so.
    I've got some test loads ready for that rifle; I just need the wind to get down to a dull roar here in ND.
    It's all a game of getting the harmonics right, and it seems the stars just don't align sometimes. The good news is there are other constellations to look at. Your rifle may want Barnes, Berger, or Sierra. You gotta play a bit sometimes.
     
    Last edited: Jun 12, 2012
  9. royinidaho

    royinidaho Writers Guild

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    Some barrels are simply "slow". I've had two Lilja, noted for tight bores, barrels on the same rifle. The shorter 28" barrel gives identical velocities as the 30" barrel with two or three grains less powder.

    I have another rig, 270 Win with a 10 twist Lilja that reaches "pressure" suddenly and way too soon. This is the second barrel on the rifle. The first was a Douglas premium circa 1966 chambered by a local smith. I can't match the 24" Douglas velocities with the 27" Lilja. Hmmm

    However, this 270 Win with 55 gr 7828ssc gave a 3-shot string velocity of 2998/3006/3016 w/158 grain bastardized Nosler Balistic tips. Too bad it was way over pressure. Droping 3 grains would be about right.

    Thus, I chime in with "may be that your barrel is simply slow????
     
  10. Snowfighter

    Snowfighter Well-Known Member

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    It is possible that I might have a tight barrel.
    Also very likely I need to try other bullets. Just was hoping I could get the amax or burgers to sail true.
    Any other ideas?
     
  11. TOM H

    TOM H Well-Known Member

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    I'd read one of your early post about shooting 900yds with the 280AI and all seemed to be fine then.

    I would assume you have talked to your gunsmith during the build as to bullets/twist and throating and the problems your now having?

    I'm not sure I'd have patience trying 11/12 powders with two bullets without stepping back and rethinking something may be wrong either with my reloads or the rifle or just me.

    I have one 280AI with a Kreiger barrel other one has Lilja and loading data came from Nosler manual the Krieger barrel set up for 150gr. In the Lilja barrel 280AI I've shot IMR-7828ssc with 160gr AB 1gr under max(60.5gr) @ 3058fps and the start load 57.5gr @ 2916fps. I've also tried R-17 in the Lilja barrel 280AI I started 53gr/R-17/160grAB @ 2834fps and 56gr/R-17/160grAB @ 3046fps and with both powders if I change over to a Fed 215M from Fed 210M I'd gain appr 50fps.

    I had both 280AI custom throated. I just had Kreiger barrel put on my 2nd 300WSM first one has Broughton barrel and I have to say been good barrels on my rifles.
     
  12. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    What is your barrel condition? If it has copper fouled, that could explain a big part of this. Have you given the rifle to another experienced shooter for a group or two?? I sometimes do this with a rifle I'm pissed at; they don't know to be pissed at the gun and shoot better. It seems like you shoot better chasing other peoples groups with your rifle.

    Tom H has a point --
    "I'm not sure I'd have patience trying 11/12 powders with two bullets without stepping back and rethinking something may be wrong either with my reloads or the rifle or just me." quote
     
  13. Shumba

    Shumba Well-Known Member

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    It sounds to me like there is an issue with your barrel. Have you called Kreiger about it? I am shooting over 60 g of 7828 for both the 168 and 180 Bergers at 3000 and 2900 respectively, and I am a below max. The 56g load you are shooting is max in a std 280 but should be nowhere near max in an AI case. I would consult your gunsmith and Kreiger. Good luck.
     
  14. Forrest Ebert

    Forrest Ebert Well-Known Member

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    Hey Snowfighter you never mentioned what twist you have in your barrel? There are a lot of us here shooting the 280AI and quite a few are using 63.0-63.5 grains of Retumbo with a 168 Berger Hunting VLD and out of a 26" tube you should be in the 2900-3050 area if your twist is right! What brass are you using as well as most are using Nosler with either a standard or magnum primer. I agree the load you listed sounds like for a standard 280 as you can start at the standard 280's max and work up or figure around 5%-8% more powder per load. Hope this info helps.