270 Allan Magnum?

Discussion in 'The Basics, Starting Out' started by 270yotekiller, Sep 14, 2005.

  1. 270yotekiller

    270yotekiller Well-Known Member

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    I hear about this 270 Allan magnum and well i used the search function here but can't find basic information about this cartridge so can someone point me in the right direction, thanks alot!
     
  2. ss7mm

    ss7mm Writers Guild

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    Re: 270 Allen Magnum?

    270yotekiller:

    Type, or copy and paste, the following into the search screen box. Set it for a couple of years and sit back and read.

    +270 +allen +magnum

    If you have any questions contact Kirby via e-mail at: kballen@3rivers.net
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    270yotekiller,

    Let me know what questions you have and I will answer them for you.

    Kirby Allen(50)
     
  4. 270yotekiller

    270yotekiller Well-Known Member

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    What kind of case is used to make the 270 AM?
    can a 270AM fit in a regular long action?
    What barrel type/length/twist/etc do you recommend for this caliber?

    Thanks guys

    PS, the search function for 270+allan+magnum retrieved a bunch of information about peoples own rifles, etc but nothing on the cartridge itself how to load it etc, just a bunch of stories that only help to intrigue me but not satisfy my curiosity.

    Thanks
     
  5. sewwhat89

    sewwhat89 Well-Known Member

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    Its based on a 300 RUM I believe. Send Kirby an email, and let him answer all your questions. He can include some pictures of the cases for comparison to stuff you are familiar with. They are worth 10,000 words!

    Stephen
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    270yotekiller,

    The 270 Allen Mag is based on the 7mm RUM case. Since I designed and built several of these rifles I have since become aware of some slight headspace variations in the 7mm RUM brass.

    As such, I not recommend using 300 RUM brass as the parent case. This allows for a more positive shoulder to provide a gas seal should the original headspace measurement of the parent case be a bit short.

    Basically with the 300 RUM case, you can set the correct headspace for the fireforming loads. With the 7mm RUM you are pretty much at the mercy of the factory spec ammo.

    Also, using the Federal 300 RUM cases has also produced good results if you can find this bulk brass.

    The 270 Allen Mag is best suited to the Rem 700 RUM receivers but any long action receiver can work as long as it has a magnum bolt face. I do recommend RUM receivers if a repeating rifle is desired.

    Savage receivers work great but you will be limited to single shot rifles as the fat shoulder does not agree with the Savage magazine system, even in RUM chambered receivers.

    I recommend Lilja barrels for all of my custom rifles. Any top quality barrel will work though. I did have Dan Lilja tool up to build 1-8 twist 3 groove barrels specifically for my 270 Allen Mag.

    THis fast 1-8 twist will easily handle the big 169.5 gr ULD RBBT and there is also a 185 gr ULD RBBT in the works from Wildcat Bullets for this round as well as the new to be released 277 Allen Mag.

    If you will be shooting conventional bullet weights, the standard 1-10 twist is great. In 30" barrels the 270 AM has been able to drive the 140 gr Accubond to 3625 fps!!! THis is a hot load but you may have read the report of a mountain goat recently hammered with this combo. Seemed to work great!!!

    If you want the extreme range performance, the 1-8 twist is the best way to go as it will allow you to use the heavy 169.5 gr ULD RBBT as well as the new 185 gr ULD RBBT when it comes out. You can also use conventional bullets in this twist as well such as all the Ballistic Tips and the 140 gr Accubonds. Thin jacketed bullets may not be able to handle this fast twist.

    Let me know if you have any other questions and I will give you all the information I have.

    Kirby Allen(50)
     
  7. 270WSM

    270WSM Active Member

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    I have a question Kirby, 277 Allen Mag ????? Give us details /ubbthreads/images/graemlins/laugh.gif
     
  8. Eaglet

    Eaglet Well-Known Member

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    Kirby,
    you are saying you do recommend using the 300 RUM cases correct? Just to make sure 100%.
     
  9. lerch

    lerch <strong>SPONSOR</strong>

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    Yote Killer, I would highly recommend you get this 270 AM if you want a true long range hammer,

    If you do get it don't fart around with any bullet other than the 169.5 ULD. I am sure all the other bullets work great but trust me, this bullet/ rifle combo is on another planet.
    I have shot 3" groups at 800yds with fireforming loads and I managed to land 2 shots within inches of eachother at just shy of 1700yds with the full tilt loads.
    I am in no way trying to bad mouth this round with bullets other than wildcats, I am sure it does great. But with these ULD bullets it is just above and beyond anything else.
    Hopefully in a month I will be posting some pics of what it does to a whitetail but we will have to wait a while.
    As for loading i used the 7rum brass and necked down 3/4 of the way to leave a good crush fit. We used 97gr of WC-872 powder for the fireforming, this gave about 3250-3300 fps which is a lot of thump for something on the other end of the bullet. Just check out our post about pdog shooting and BJ shooting the cow.
    I settled on 104gr of WC 872 for the full bore loads and I actually haven't chronod them yet but I am sure it is around 3450.

    It is a hell of a round and Kirby builds a hell of a rifle so I am sure you wouldn't be dissapointed if you get one.

    Take it easy
    Steve
     
  10. srhaggerty

    srhaggerty Well-Known Member

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    I second what Lerch said. This is a great cartidge. I used the 140 grain accubonds for a brief amount of time to take a Mountain Goat as Kirby pointed out. I plan to switch to the 169.5 ULD's this winter. Then hopefully I can take a deer, elk, and maybe a cow moose with that combo.
     
  11. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    270WSM,

    Simply put, its a 7mm Allen Mag necked down to 270. Based on the Lapua and designed to be used with the new to be released 185 gr ULD RBBT.

    More to come on this little jem soon!!

    Kirby Allen
     
  12. davewilson

    davewilson Well-Known Member

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    50,
    someone asked and i would also like you to clarify regarding the headspacing on 300 brass compared to 7mm. i thought about trying some federal 300um brass sized for my 7um.is it a bit longer or is any 300 brass a bit longer than the 7 ?
     
  13. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Dave,

    On paper, the 7mm, 300, and 375 RUM all have the exact same headspace measurement. Meaning the only difference dimensionally between the three is the neck diameter and the resulting neck length.

    That said, what is printed on paper and what makes it out the door from Rem are at times two different things unfortunately.

    I recently encountered a batch of 7mm RUM cases that were roughly 0.010" shorter from the rim to the shoulder/neck junction then any others I have used in the 270 Allen Mag.

    As there is only a 0.007" deduction in the 7mm RUMs neck diameter to that of the 270-7mm RUM(fireforming load), this is not enough to produce a positive shoulder to gas seal off from. Even if you only size the first 2/3 of the case neck this is not enough to limit case stretching.

    The problem is that I generally use match grade striker assemblies in my Allen Magnums and with the heavier striker spring, when the striker impacts the primer, it will drive the case forward in the chamber until it is physically stopped by the case shoulder. Normally, the 0.004" crush fit built into these chambers totally eliminates this problem but when the parent case has its shoulder set back 0.010" farther to start with you can not control this.

    The resulting fireformed brass will have a slight thinning just ahead of the case head, the start of case head seperation.

    Now if you only neck size or partial FL size this is not a real concern but it is an issue that is easily corrected by using 300 RUM brass instead of the 7mm RUM at least this was my thinking so I tested it out.

    Everything seemed to work fine, even case neck thickness was not a problem, in fact it tightened the chamber to neck fit up by a couple ten thou while still allowing enough room for safe bullet release on firing.

    Best of all, no matter where the factory shoulder is located, using 300 RUM brass, when you neck the case down to 270 you can position that neck where ever you want to offer a positive gas seal which will eliminate case head stretching.

    I do recommend that you make sure the neck diameter is such that will work safely in the rifle though before heading to full tilt loads.

    The 300 RUM from federal should work fine in your 7mm RUM. Just check for case length after sizing and neck diameters as well. You may need to turn your necks slightly but I doubt it. Still, check before you start shooting.

    Kirby Allen(50)