510 Allen Magnum...

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Fiftydriver, May 15, 2006.

  1. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    To all,

    Well, with the 338 AM in the hands of Fed Ex and on its way to get its final finish of teflon applied by Shawn C. I just received good news that the barrel for my next project will be arriving today.

    Now my past Allen Mags have been designed for extreme performance big game hunting rifles. While they are extreme in performance I always wanted to keep them practical to use at least for the relatively experienced handloader as far as case forming and such things were concerned.

    Well, my latest project is a little different. I really did not care on this one as it will be much more of a "need to have the biggest thing around" type of a rifle. I have shot the 50 BMG rifles for alot of years and they are alot of fun. Once you shoot a BMG its hard not to start pricing rifles and saving up.

    Once you get into the big 50 more and more you realize that accuracy and consistancy can be extremely high quality in spite of the many handicaps facing the big 1/2" round.

    I have always wanted to wildcat the 50 cal and several months ago, Richard Graves and myself were spending each others money again and came up with an idea, again a partnership between his bullets and my case design.

    The 50 BMG round is generally loaded to 50,000 to 55,000 psi by todays bolt action shooters. At times even less then this with bench shooters. Our idea was to design a wildcat that would offer near 3000 fps velocity potential with a 750 gr bullet weight.

    Better yet was that we wanted to shoot bullets in the 835 to 1000 gr bullet weights in this new design. This was as much a nessesity as it was a desire to try some heavier bullets. The reason is because of the wildcats case design.

    The 510 Allen Mag has basically all the same case configuration as its much smaller siblings except a bit more body taper to counteract the huge baring surface for good extraction with high pressure loads.

    Case capacity is estimated to increase by 45 to 50 gr of powder in the fireformed 510 AM case compared to the 50 BMG parent case.

    Also, I designed the chamber quite tight for a 50 cal chamber to help allow the 510 AM to work at higher working chamber pressures. Nothing extreme here. There is no design to run this BMG case to 70,000 PSI but I do feel we can get into the 60 to 65,000 PSI range easily with the chamber design and case body design with no extraction issues.

    What I really wanted was the ability to drive a 835 gr class ULD RBBT to the same velocities which are common with a 50 BMG bench rifle using a 750 gr A-max. Basically we are looking at a velocity of between 2500 fps and 2675 fps depending on how the handloader wants to load the 50 BMG. In all honesty, I want 2700 fps with an 835 gr bullet and I am hoping for 2400-2450 fps with a 1000 gr ULD RBBT if the twist will handle it.

    When I started the project, I wanted to initially order in a McMillan BR single shot receiver along with a McMillan 50HBR stock for a rifle that would weight close to 50 lbs. THe more I thought about it though, the more I thought a lighter weight version would be much more practical for field use.

    I wanted a full length bolt action receiver which could be fully accurized and used in a conventional manor. I had an LAR grizzly which was a great shooting rifle but the shellholder type receiver left a bit to be desired for shooting as it really slowed down the process and also required you to come off the rifle between each shot. I did not want this.

    I really did not care about a repeating rifle as I am plenty used to single shots in the field. No disadvantage in my mind using a single shot.

    I started looking at difference actions and complete rifles for donor actions and finally settled on the Armalite AR-50. I liked the way the receiver was designed although it was not the best looking receiver around it had the features I was looking for:

    Full Length Bolt Action
    Easily accurized
    Used Rem 700 trigger assemblies
    3 lug bolt head

    Other features I liked was the design of the receiver which is machined with a deep V on the bottom of the receiver which rides in a V-Block in the stock. Basically as close to a machine rest as you can get and still use a stock.

    [​IMG]

    [​IMG]

    The receiver is very large. In fact it is one of the few receivers I know of and the only one I own that actually makes the 2"x10" BAT look on the small side!!! These two pics compare the AR to a LA Rem 700.

    The receiver is a full 14" in length and its 2" in diameter measured on the octagon flats of its receiver.

    The bolt of this receiver is just shy of 11.5" long itself and is a huge 1.375" in diameter. The bolt lugs are also this diameter.

    The recoil lug fits right in with the receiver being a full 0.750" thick with a 1" deep foot.

    [​IMG]

    [​IMG]

    The bolt is also fitted with a very large Sako style extractor for positive extraction of the big cases.

    The AR receiver is actually much larger then it really needs to be for the 50 BMG cartridge. In fact it was designed for the much longer Russian version of the 50 cal military round.

    When I heard the news that the barrel was coming I pulled the barrel from the AR-50 to inspect the receiver for truing. I was totally suprised when I measured the variance across the bolt face from the receiver face.

    Three of the four measurements on the bolt face(12:00, 3:00, 6:00 and 9:00) were all within 0.0001" and the four measurement opened the variation up to only 0.0002" across the bolt face which is my limit for a receivers squareness.

    I was also suprise to see the huge recoil lug was consistant in thickness to less then 0.0001".

    Basically I decided the barrel was fit to build on as it set and as positive side note. If I ever decided to sell the rifle again, the new factory barrel could be reinstalled and get full market value for the rifle.

    I am hoping to get working on the 510 Allen Mag assembly next weekend. Just wanted to update you on the start of another AM that will be released soon.

    Again, this is a project in shear power at long range. Not the ultimate flat trajectory but shear HorsePower with Heavy bullet at long range.

    More to come soon from this new monster!!!

    Kirby Allen(50)
     
  2. lerch

    lerch <strong>SPONSOR</strong>

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    I am terrified!!! Yet I cannot look away!! /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

    That should be a serious finger of God type gun!!! Someday you are gonna run out of juice up and then we are all gonna be in trouble!

    take it easy
    steve
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Steve,

    YOu and BJ will be getting some formed cases as soon as they are formed and get those dies rolling.

    Should be fun. Talked with a guy that was using a 50 BMG Imp and was getting 2933 fps with a 750 gr pill in a 32" barrel. It looks like near 3000 fps in my 34" pipe will be a possibility.

    Just have to see if I am man enough to handle the recoil. may have to send it up North to Richard, he is crazy about big rifles!!!

    More man then I am!! /ubbthreads/images/graemlins/grin.gif

    Kirby Allen(50)
     
  4. lerch

    lerch <strong>SPONSOR</strong>

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    Cant wait to see those cases!!!

    What kind of accuracy can you expect out of a custom 50, i have no real experince with them and I dont know what they are capable of.

    3000fps with a 750gr bullet would be absolutly amazing!!!

    keep us updated
    steve
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Steve,

    Accuracy wise, lets just say the world record five shot group at 1K is just over 2" from a heavy rifle. I have personally shot 7" groups at 1000 yards in my LAR Grizzly with quality hand loads.

    I would say they are just as accurate as other chamberings but they are often much more difficult to shoot accurately because of the level of recoil and muzzle blast.

    It makes me laugh when I hear guys saying that since its a 50 BMG then making a hit at extreme range is easy!!

    First sign they know nothing about the big guns. If you can hold tight groups with a 50 cal bolt gun, you are a fine shot. If you can load ammo for the 50 that produces tight groups you are a fine handloader.

    They are not the easiest rifles to load and shoot with match grade accuracy but that is not because the round or rifles are not accurate by any stretch of the imagination. 1/2 moa is still plenty realistic at any range really in a quality rifle with quality ammo.

    Trajectory is not the flattest but who can argue with 15,000 ft/lbs of energy /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif!!

    Again, this is a shear horsepower thing but if its not accurate I would not be interested in it at all!!

    Kirby Allen(50)
     
  6. mindcrime

    mindcrime Well-Known Member

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    [ QUOTE ]
    Just have to see if I am man enough to handle the recoil. may have to send it up North to Richard, he is crazy about big rifles!!!

    More man then I am!! /ubbthreads/images/graemlins/grin.gif

    Kirby Allen(50)

    [/ QUOTE ]

    Send that Mutha over here to Tennessee and I'll test fire it for you. /ubbthreads/images/graemlins/wink.gif I'm still sporting a nice bruise from practicing rapid fire with my .416 Rigby / Ruger RSM last weekend!!! /ubbthreads/images/graemlins/grin.gif
     
  7. Black Diamond 408

    Black Diamond 408 Well-Known Member

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    Kirby,

    I can feel my neck and back tightening up just reading the post! KaBooooooom

    Shooting the big 50's is very fun, specially if you have a chiropractor friend along! /ubbthreads/images/graemlins/blush.gif

    I have never shot a heavy 50 rifle, just the one i had, 29# and a bad muzzle brake! But still it was a rush to pull the trigger, just another form of cocaine. I love shooting big guns! Some day i will get out your way and have a blasting party!

    Later..

    Dave
     
  8. JD338

    JD338 Well-Known Member

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    [ QUOTE ]
    Kirby,

    I can feel my neck and back tightening up just reading the post! KaBooooooom

    Shooting the big 50's is very fun, specially if you have a chiropractor friend along! /ubbthreads/images/graemlins/blush.gif



    [/ QUOTE ]

    I don't think you will need a chiropractor. /ubbthreads/images/graemlins/grin.gif

    Should be fun. Keep us posted.

    JD338
     
  9. JKO

    JKO Well-Known Member

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    JD338:

    Maybe Kirby won't need a chiropractor, but he might need an orthopedist to put his shoulder back into joint after he touches that thing off.

    /ubbthreads/images/graemlins/tongue.gif

    --JKO
     
  10. Ridge Runner

    Ridge Runner Well-Known Member

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    Hurry up and "GIT-R-Done" kirby, then you'll hafta build a 20 mm vulcan Allen express. Then I'll order the next one, how the hell ya gonna Allen Improve a patriot missle? LMAO!
    JS
     
  11. James Jones

    James Jones Well-Known Member

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    Kirby , what brake do you intend on using for that rascle? the only 50 I have ever fired was Robar RC-50 it weighed in at around the 30lb mark , with handloads scaring 2900fps with the 750 gr A-max the recoil was not bad at all compaired to many deer guns I have shot , their brake is very effective. Now the muzzel blast scared the hell out of me the first time I fired it , I thought something had blown up or a massive case failure , the know the blast is bad when a couple shots plugs your sinuses.
    I can probably round up some 12" lengths of 416 SS up to 2" if you wanted to build your own brake. I have 24" of 2.5" Titanium but I'm hording it in hopes to build a couple actions one day
     
  12. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    James,

    I was originally going to take the 50 cal Russian round and use that case, quite a bit longer then the 50 BMG and would offer siginificantly more capacity but cases are just to hard to get ahold of and spendy.

    20mm.................

    Good idea /ubbthreads/images/graemlins/grin.gif!!!

    Kirby Allen(50)
     
  13. abinok

    abinok Writers Guild

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    Theres always the 14.5mm soviet... or you could follow McMillans work on the 50fatmac and do a shortened 20mm.
     
  14. mindcrime

    mindcrime Well-Known Member

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    [ QUOTE ]
    [ QUOTE ]
    Just have to see if I am man enough to handle the recoil. may have to send it up North to Richard, he is crazy about big rifles!!!

    More man then I am!! /ubbthreads/images/graemlins/grin.gif



    Kirby Allen(50)

    [/ QUOTE ]

    Send that Mutha over here to Tennessee and I'll test fire it for you. /ubbthreads/images/graemlins/wink.gif I'm still sporting a nice bruise from practicing rapid fire with my .416 Rigby / Ruger RSM last weekend!!! /ubbthreads/images/graemlins/grin.gif

    [/ QUOTE ]

    Here's the BRUISE! /ubbthreads/images/graemlins/grin.gif [​IMG] On the last shot, the pad slipped over to my bicep, what a mistake. /ubbthreads/images/graemlins/blush.gif I have heard that I need a Limbsaver recoil pad. What do you fellas think??? /ubbthreads/images/graemlins/smirk.gif