Building a 300 win mag.

Discussion in 'Gunsmithing' started by boattailed bandit, Jan 26, 2014.

  1. boattailed bandit

    boattailed bandit Well-Known Member

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    So I've got a browning a-bolt 270 that I love. I shoot with it all the time and I hand load for it. But I know that eventually its going to be time to re-barrel it. I would like to go to a different caliber when I do and I'm looking really seriously at the 300 win mag. I have limited gunsmithing experience so my question is if I get a barrel chambered for 300 win mag, and a bolt/ bolt face for 300 win mag would that be all I need to do? Just looking for some guidance as to if this is how to do it and if not what do I need to do to make this work? Is it even possible at all?
     
  2. MagnumManiac

    MagnumManiac Well-Known Member

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    I'm not familiar with Browning actions, but just having the bolt face opened and a new barrel fitted may not be all that is needed, because a 300WinMag is larger in body diameter you may find you will have to open the feed lips and modify the feed ramp so the cartridge doesn't hang up or jam.

    Wouldn't it be easier just to buy a rifle in 300WinMag and have the best of both worlds?

    That's what I would do, I have 3 300WinMags and love all 3, all are very accurate and pose no problem regarding handloading and brass life.

    Cheers.
    gun)
     

  3. FEENIX

    FEENIX Well-Known Member

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    +1! I have 2 .300 Win Mags and are my go to chamberings.

    I've re-barreled my .270 Win into .270 AI with Lilja 30", 3-groove, 1:8" and currently pushing 175gr Matrix VLDs at 2993 FPS as my accuracy load (at least for now) ... that's up there with performance level of a factory 7MM Rem Mag pushing 180gr HSM Berger VLD at 2845 FPS. :D
     
  4. boattailed bandit

    boattailed bandit Well-Known Member

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    What all would a person have to do to their casings for 270 AI? And does it still through the .277 bullet? Anything that's not a stock round I consider a wildcat round and therefore know nothing about them.
     
  5. J E Custom

    J E Custom Well-Known Member

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    The easiest upgrade would be to a 280 AI (Same ballistics as the 7mm Rem Mag) with no change in the bolt face or feed rails.

    It Would be a straight forward re-barrel job. Everything else would stay the same. The 280 AI also does well with 180 grain bullets and BCs are great.

    Just a thought if you want to minimize the work and cost and keep the rifle you have.

    J E CUSTOM
     
  6. boattailed bandit

    boattailed bandit Well-Known Member

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    So what would a person do about brass? I assume you could buy it, but what would it start out as? If it's just trimming and becoming it down I might have the brass around to do that.
     
  7. FEENIX

    FEENIX Well-Known Member

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    You don't have to go wildcat at all. Re-barrel with 26-28", 1:9 for the 165 Matrix and 170 Berger or 1:8" for the 175 Matrix and the previous bullets noted and your golden. You already have the rest.

    I am pushing the 175s at 2919 FPS while fireforming out of 30" barrel.
     
  8. J E Custom

    J E Custom Well-Known Member

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    If the 280 AI is head spaced right you can buy standard 280 Remington ammo and fire form it while you hunt,
    or buy 280 brass. It is a shoot and reload without trimming or anything.

    The reason I recommended the 280 AI is the increase in power, and a great selection of 7mm bullets
    also The case life is better with the AI than the standard shoulder of the 270,280,30/06.

    The average velocity of a 270 with a 150 grain bullet is 2700 to 2800 ft/sec.
    The 280 AI average is 3000 to 3100 ft/sec with the 150 grain bullet for a 2 to 300 ft/sec increase
    and a couple of hundred yards more of trajectory and energy.

    J E CUSTOM
     
  9. boattailed bandit

    boattailed bandit Well-Known Member

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    So the standard bolt face on a 270 will work with the 280? Just wanting to make sure because I think this might be what I do.
     
  10. FEENIX

    FEENIX Well-Known Member

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  11. boattailed bandit

    boattailed bandit Well-Known Member

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    Ive read that article once or twice and it makes me want to keep using my 270 :). I just worry about effective energy when hunting. My farthest shot would probably be 800 if I was ever lucky. Im not overly concerned about taking long shots on steel, but I don't believe in injuring game. Im not 800 ready yet, I still need more practice, but when I get to that point I want something I wont have to worry about. Ive gave thought to just another 270 barrel in a larger contour when its time. There's just so many options. haha gun)
     
  12. FEENIX

    FEENIX Well-Known Member

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    I could be wrong but Rhian probably has the most experience and success with the 165 Matrix in .270 Win and WSM. Below is an extract from one of his many posts/threads ...

    Hopefully, he'll chime in too!
     
  13. clambdin

    clambdin Well-Known Member

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    JE Custom makes a good point...I would recommend the 280 AI also..I have one and also have a 300 win mag, I shoot the 280 Ackley twice as much as the 300..Plenty of energy with less recoil and brass life is forever...
     
  14. Clark

    Clark Well-Known Member

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    The biggest bull elk I ever saw was shot by a tiny woman with a .243 and a baby.

    I know a 63 year old guy that finally got a shot at a bull elk this year with his 300 WM.
    He just wounded it, it ran over the hill, and some young guy stopped it with a 22-250.