6.5 ultra mag ballistics?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 1doug, Feb 25, 2005.

  1. 1doug

    1doug Well-Known Member

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    Kirby do you have any ballistics for your 6.5 KAM? Is it essentially a 6.5 ultra.If so can you neck down A 7 mm ultra for what You are doing? I am interested in building one on a left handed Bat Action ( remmys Hard to come for us southpaws) anything I need to know before i start my adventure? also what is the largest wildcat bullet for the 6.5?
     
  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    D-a,

    The 6.5mm Allen Mag is based on the 338 RUM case which is shorter then the other three RUM cases by 0.090". I used this case because I wanted to sharpen the shoulder angle and if I did this with the longer cases, the case capacity would be to large for the 6.5mm bore.

    As is the 6.5-338 RUM holds around 116 gr or H-335 filled to the case mouth, the fireformed 6.5 Allen Mag will hold right at 123 gr.

    Ballistically, you will get the following with a 30" barrel:

    100 gr...............4100 fps
    120 gr...............+3800 fps
    140 gr...............+3450 fps


    Wildcat Bullets is as we speak designing bullets for the Allen Mags that will weigh 169.5 gr and have a B.C. in the mid .900 range!!!

    These have yet to be tested though.

    I will be supplying prenecked, annealed brass for $38.00 per 50. All you will need to do is fireform, trim and your ready to roll.

    Dies will be in stock from me in May.

    Good Shooting!!

    Kirby Allen(50)
     
  3. chris matthews

    chris matthews Well-Known Member

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    Gotta question- could be way off base here but 116 gr of H335 sounds like to me it would blow up something in such an overbore case. I guess what I am trying to say is, isn't H335 a bit fast for this round? Maybe a typo- or did I miss something?
     
  4. 1doug

    1doug Well-Known Member

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    Kirby, who do you get to make your reamers? I was thinking about a manson removable pilot. Also what shoulder angle are your cases and how much taper does the case have?

    Thanks D-A
     
  5. Brent

    Brent Well-Known Member

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    Chris,

    I think Kirby was just making a comparison in case capacity between a simple necked 6.5/338 RUM case and that of his IMP design, H335 was just used as a capacity example instead of water.
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Chris,

    You are 100% correct, I just used this powder to get an idea of case capacity comparing the virgin case with the fireformed. I generally use BLC-2 but did not have any on the bench. H-335 settles so evenly and consistantly it does nearly the same job.

    Just easier to use powder then water, especially in cases I want to load up "now".

    You are right, NEVER USE H-335 IN THE ALLEN MAGNUMS!!!

    Sorry for the confusion should have stated this in the original post.

    Kirby Allen(50)
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    D-a,

    Not to be a snit about it but I can not tell my shoulder angle, keeping it secret. Will say that body taper is very min, roughly 0.012" over the length of the case body. Can be tricky to chamber with such min taper, lots of time, lots of oil and mostly lots of patients to get perfect chambers.

    Manson will make you a fine quality reamer, as will any of the other top name reamer makers, I use JGS exclusively and have never been disappointed.

    I would highly recommend them.

    Also, a live pilot reamer is the only way to go for extreme accuracy in a rifle. Also get a full set of pilot bushings or at least the ones you will need for your barrels bore diameter. Use as large a pilot bushing as possible while still allowing an easy slip fit into the bore.

    Good Shooting!!

    Kirby Allen(50)
     
  8. chris matthews

    chris matthews Well-Known Member

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    Okay, thanks Kirby. I was pretty sure of that but was a little concerned about it for those who were less experienced that visit here.
     
  9. 1doug

    1doug Well-Known Member

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    Fifty thanks again, was not trying to infringe on your design, just I am wanting to build a 6.5 rum with a 35 degree shoulder angle with minimum body taper. Your 6.5 Allen Mag seems very close to what I am lookin to build.

    D-A
     
  10. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    D-a,

    Yes it is very close to that but let me warn that I would highly recommend not going with the full length RUM case such as the 7mm, 300 or 375 which are longer then the 338 RUM case.

    YOu will be limited to using ball powders such as H-870, AA8700 and the very slow surplus powders such as 872. This is not a problem as they work very well btu you will have a powder bridging problem with a shoulder angle of this degree or sharper.

    That meaning when fired the powder charge will compress and wedge in the shoulder-neck junction of the case and cause soem severe pressure variations. I tested Retumbo and even H-50BMG in mine and experienced this problem. One shot would show no pressure signs at all while the next would blow the primer pocket.

    This is not a problem at all with the ultra slow ball powders listed so keep this in mind, will save you time and headaches down the road.

    Now my 270 Allen Mag did not have this problem due to the larger bore, still 8700 works extremely well in this.

    Other benefits of the ball powders is they burn much cooler then stock powders and are much less abrasive as they are forced through the throat of the rifle. A major consideration in case life when your burning +100 gr or powder in a 6.5mm bore.

    Good Shooting!!

    Kirby Allen(50)
     
  11. Guest

    Guest Guest

    Kirby,
    I have followed your progress on the .257 AM, but didn't realize that you were also working on a 6.5mm. Per our previous discussions, I'm definitely interested in one or both. What kind of numbers do you get when you compare the 257 &amp; 6.5???
     
  12. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Nighthunter264winmag,

    Basically with the new Wildcat bullets, the two are very similiar. Both have bullets that will hit 4100 fps, both have bullets that will push or exceed .900 in B.C. as well.

    The 6.5mm Allen Mag will do anything the 257 version will do with the same bullet weights and add roughly 35 to 50 fps to top velocity levels, or it will push a 5 to 7 gr heavier bullet to the same velocity as the 257.

    They are very similiar with the Wildcat Bullets, I designed them both simply because there was no high performance option for the 257 caliber and the 6.5mm is so popular now youwould be stupid not to offer one.

    Good Shooting!!

    Kirby Allen(50)
     
  13. mike33

    mike33 Well-Known Member

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    What do you mean by no high performance option for the 257
    mike
     
  14. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Mike,

    You really went digging for this old post. Are you looking for things to do?? LOL

    My comment was directed toward the lack of commerically available high BC 257 bullets on the market compared to the 6.5mm which has several "good" BC bullets that are easily attainable. At least I think that is what I ment rereading the post. That was a LONG TIME AGO!!!

    Take care,