510 AM test

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Fiftydriver, Jul 28, 2006.

  1. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Well, Here is another tease. This is the first FULLY formed 510 Allen Magnum case. Took some playing around with loads and shoulders must be annealed to form sharply but we figured it out.

    [​IMG]

    On right is a standard 50 BMG 647 gr BALL, 510 Allen Mag loaded with the 835 gr ULD RBBT in the middle and the 7mm Allen Mag on the right for size comparision.

    I will post on the performance and accuracy results here soon. What I will say however is that we have the ability to reach the 7 1/2 tons of muzzle energy limit with this round in a 35" barrel.

    Kirby Allen(50)
     
  2. sure shot

    sure shot Well-Known Member

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    [ QUOTE ]
    7 1/2 tons of muzzle energy

    [/ QUOTE ]
    Thats it! /ubbthreads/images/graemlins/grin.gif That thing is sick, but I'm saving my money for the 20mm AM. /ubbthreads/images/graemlins/wink.gif
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I was testing the rifle with Richard Graves and Rob,a friend of ours.

    Fireforming loads using 215 gr H-50BMG under the 750 gr A-Max were producing an average velocity of 2455 fps and litereally one hole groups at 100 yards! The temp was around 90 degrees so we were only shooting two shot pairs for fireforming but every pair shot on paper at 100 yards had to be looked at at under 15 yards to tell if there were actually two bullet holes there. I was amazed to be honest.

    We then started loading the formed 510 Allen Magnum cases. TO do so, since I do not have the dies made yet, I machined a neck sizing bushing that threaded into my press extention which I use to form 408 CT cases into 338-408 cases to fireform in my 338 Allen Mag.

    The neck sizing insert worked perfectly and run outs were actually pretty good for such sizing techiques and tooling.

    Seating bullets on the other had was about as crude as could be. The 50 BMG and 510 Allen Mag are so long that even in the RCBS Ammomaster press and my extension threaded into the top of the press, the bullets would reach proper seating depth well before the ram would reach the top of its stroke.

    As such, I had to mark every bullets ogive at 0.505" diameter and then measure from the case head to the ring on the bullet ogive to get them to proper seating depth. I will admit this is about as inconsistant as it gets but thats all I had at the time to seat bullets with.

    It took some time but most test loads were held to within 5 thou in seating length.

    We started with the same 215 gr fireforming load but in these rounds we used Richards huge 835 gr ULD RBBT Soft point. Here are the velocity results for each load. These are two shots for each load:

    215 gr............2375 fps
    220 gr............2420 fps
    225 gr............2540 fps
    230 gr............2610 fps
    235 gr............2668 fps
    237 gr............2700 fps

    Accuracy wise, I was a bit unimpressed with the starting loads, Richard was sick to his stomach!!! We were getting severe vertical stringing with the first two test loads. But knowing that Richards bullets tend to shoot much better the harder you push them, we were a bit down but no where near giving up.

    At the 215 gr and 220 gr load level, we were getting 8 to 10" vertical stringing for the pairs of shots.

    At 225 gr the spread dropped to around 4" and at 230 gr the pair again tightened to a 2" spread.

    At 235 gr, the two shots cut each other in half, doing just as the A-Maxes were doing but with 150 fps more velocity and 85 gr more bullet weight.

    I had two rounds left at the 237 gr level and decided to shoot then at the same target as the 235 gr loads. First shot again cut the two previous shots and the second landed 3/4" off the group but to be fair the barrel was getting VERY warm and I was getting a bit jumpy from the recoil which is not bad at all but mentally it wears on you being pushed that much while shooting.

    Both Richards and my spirits rose dramatically after seeing that. Three shots well under 1/2" at 100 yards and the fourth opening things to 3/4" pr so out of a hot dirty barrel.

    We were experiencing one issue that I wanted to correct and that was the shoulders which were retaining a rounded shoulder on the body/shoulder junction. The shoulder/neck junction, by design has a relatively large radius but I wanted the shoulder to sharpen up and even with top end pressures this was not happening.

    We talked it over and we decided to anneal a case, just at the shoulder and see if this helped. I also used a pretty stout low consisting of 245 gr H-50BMG which was a full 8 grains over what we had topped out on the range test.

    We just went out beside my shop and shot into the big cotton wood stump I use for a bullet stop, yes, it is 50 cal proven!! Big stump!!

    At the shot everything was normal. Just a hint of a pop was needed to pop the bolt over the mechanical cam in the receiver but extraction was effortless. Best yet, the shoulder was perfectly formed, nice and sharp.

    We did not shoot over the chrono with that load. More interested in the shoulder forming but from looking at the other data, I would estimate that load to produce in the 2800 to 2825 fps range with the 835 gr pill.

    Thats 14,540 to 14,800 ft/lbs of energy.

    [​IMG]

    Here is a standard 50 BMG on the left loaded with the 647 gr Ball. In the middle is the fully formed 510 Allen Mag with 835 gr ULD RBBT Soft Point and on the right is the "little" 7mm Allen Mag.

    [​IMG]

    Close up of the shoulder angle. Annealing was the trick, worked perfectly.

    From reading the data on Hodgdons new US869 compared to H-50BMG. IT is producing anywhere from 125 to 150 fps more velocity for any given bullet weight in the standard 50 BMG up to 800 gr so I will be testing it in the 510 Allen Mag here soon to see if that holds true for a bit more case capacity and heavier bullet as well. I can not imagine a 835 gr pill going 2900 fps but we will see what happens!!

    Kirby Allen(50)
     
  4. lerch

    lerch <strong>SPONSOR</strong>

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    That is one hoss casing, DAMN!!!!! I have only gotten to shoot one 50 in my life so far, maybe I could weasel you into bringing that big ol' boy along with you next spring for our little excursion.


    sounds nice so far, keep the reports coming

    steve
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Lerch,

    Richard tells me 1000 gr ULD RBBTs are a possibility!!! I will save those for BJ and you to play with if we make this thing happen!!

    Richard and I were talking over the velocity potential of the 1000 gr ULD RBBT and we are both thinking that near 2600 fps may be possible. We will have to see, thats +15,000 ft/lbs of energy!!

    On the other end of the spectrum, Richards short baring surface 750 gr ULD RBBTs should easily break our 3000 fps velocity goal. That is also 15,000 ft/lbs of energy!!!

    Right now back to work on customer rifles and making bushings so I can get those 338 AM FL dies in my press to give that big girl a go around with sized cases.

    Just for S&amp;G I may try to get some of the 647 gr Match Ball bullets and see how fast I can drive them in the 510 AM. The standard BMG will break 3000 fps with them so it may be interesting.

    Later,

    Kirby Allen(50)
     
  6. lerch

    lerch <strong>SPONSOR</strong>

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    Oh its gonna happen buddy, just gotta get you boys signed up to head south a little and we will be heading north a little and those little furry boys in the middle will be in a HELL of a lot of trouble!!! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

    COngrats again Kirby, you need to figure up some kind of penetration test for that hoss with those 1000gr bullets. Something like a few dozen cattle lined up in a row. YOu know BJ likes to shoot cattle!!!!

    Take it easy
    steve
     
  7. duckinalaska

    duckinalaska Well-Known Member

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    Daaaang Kirby,
    I was playing with some 20mm shells at the workplace today. Guess who came to mind? I thought, I know someone who could improove, neck down, and create a rifle to burn the keg of powder that this huge case can hold. The 20 shoots with more of an arch than the 50, but couldn't you make a record setting round with this thing? Just think of the muzzle blast that this thing would have. I'll measure the real capacity with water next week. I'm surrounded by these rounds every day, and when I saw your post I thought hmmmm. Not impossible.
    Brandon
     
  8. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Ducksinalaska,

    Do you work on the air force fighters?

    Anyway to get a few cases shipped my way to take some measurements on?

    Kirby Allen(50)
     
  9. duckinalaska

    duckinalaska Well-Known Member

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    Kirby,
    Another e-mail sent.
    Brandon
     
  10. Guest

    Guest Guest

    &gt;&gt;Richard tells me 1000 gr ULD RBBTs are a possibility!!!

    Hey Kirby, I probably missed it, but what twist? I have a new fast twist (9.5) SA 50 BMG I had built specifically for 800gr and higher pills, sub-sonics and .308 Sabot's. (no muzzle break when firing sabots).

    It only has a 30" pipe and not nearly as hot as your 510 AM, but it should be good for load dev and experiment.

    As soon as I get Richards site updated I'll email him and order some big 50 BMG pills.
     
  11. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I have a 1-15 standard twist but I believe it will work with the Wildcat bullet. If it does not work with the ULD RBBT, I am sure it will work with a ULD FB which will not give up alot in BC.

    I am not a fan of fast twist barrels in 50 cal. From the tests I have read using lead core bullets, fast twist barrels are very hard on a bullet with this amount of mass. If your using solids this is not a concern obviously.

    Kirby Allen(50)
     
  12. Guest

    Guest Guest

    Yes, that's what I've been told too. Every manufacture is using the 15 twist. I had to wait a year to get the fast twist Lothar Walther barrel. But my other three 50's have the standard 15 twist. This gun is a test mule, primarly for 308 sabots and subsonics. I'll also see how big of a pill I can shoot. I ordered the gun before the 510 AM was announced.

    I think a 1-12 twist might be a reasonable choice for 800gr+ projectiles. The 9.5 seems way overkill for a 50.
     
  13. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I would agree, if I ever get into a faster twist 50 cal barrel it will be a 1-12 or 1-13 twist. We will see how the 1-15 handles the lead cored heavies first before ordering a custom twist barrel though!!

    Have you tested your 1-9.5 yet? how did she shoot?

    Kirby Allen(50)
     
  14. Mysticplayer

    Mysticplayer Writers Guild

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    Kirby that is a monster.

    Any pics of the rifle? or should we just refer to an Abrahms.

    That is some serious horsepower.

    Great stuff enjoy...

    Jerry