7mm, 200gn Loads

Discussion in 'Reloading' started by 257speed, Oct 23, 2005.

  1. 257speed

    257speed Well-Known Member

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    Kirby, anybody, have any recommended starting loads for Richards 200gn bullet in the 7mm Ultra Mag, 1/9 twist. Hope to use Ramshot Magnum, Retumbo, ot something similar. Thanks guys
     
  2. davewilson

    davewilson Well-Known Member

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    i am also very interested in this exact same question but i plan on using the 872 powder and have a 7 twist barrel not that the twist will make any difference. also could you make any comments on the differences in using the thicker jackets of the match kings that he is now using instead of the j-4's that he previously incorporated. thanks in advance.
     

  3. sure shot

    sure shot Well-Known Member

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    Will the 200gr pill be accurate with a 1 in 9 twist? Also what is the BC on those suckers and how much do they cost?
     
  4. davewilson

    davewilson Well-Known Member

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    most of the time a 9 will probably work but it's on the edge of stability.some on here shot these and produced a BC in the .94 range. $48/100 canadian'
    Kirby,
    could you tell me the capacity difference between your 7AM case and the rum.maybe the load you're using in the 7AM and we'll figure out a starting load for our 7rum's.
     
  5. 7Rumloader

    7Rumloader Well-Known Member

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    Guys I haven't shot any yet but I'm planning on starting at about 95/96 grains of the WC872 powder being that 104.5 was max for the 169.5's in my stick. I don't know what to say on Retumbo or faster burning powders for the big 200's cause for 160 and up I have been using BMG powder and wc 872.
    That may not help you 2 any but I figured I would throw it out there.
     
  6. davewilson

    davewilson Well-Known Member

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    thanks, it helps a bunch. i'm using 872 powder.
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    257 Speed,

    I have not tested the 200 gr ULD in the 7mm RUM so I hate to give a recommendation for a powder charge. I know there are some on this board that have or are about to test the 200 gr ULD in the 7mm RUM so we should be getting some data here very soon.

    Kirby Allen(50)
     
  8. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Dave,

    Now using WC872 I would be able to offer a starting load for what I would use personally with this bullet but keep in mind that you use this data at your own risk as I have not tested this data and can not say that it will be totally safe.

    Before I get to the data lets talk about the new bullet jackets that Richard is using. Personally I feel this is a god sent that Richard got into the stouter Sierra jackets. The Sierra jacket is twice as thick as the J-4 which will greatly increase the integrity of this bullet at high velocities as well as promote better penetration.

    In resent testing, when velocities have topped 3250 fps in the 7mm Allen Mag with the J-4 jacketed 200 gr ULD RBBT, bullet failure was a problem. Anything below this the bullets seemed to perform very well.

    This is EXACTLY what I have seen with every 3 groove barrel using the J-4 jacketed bullets.

    In past testing with the Sierra jacketed bullets in the same 3 groove barrels(not in the 7mm AM though), the Sierra jacket offered at least 200 fps more velocity potential then the J-4 jacket would offer with fine accuracy.

    So personally, I feel that in the 7mm RUM either bullet will work but the Sierra will be a much better bullet for this round and needed for the 7mm AM.

    Case capacity of the 7mm RUM and the 7mm AM with both filled to the mouth with WC872 is as follows. Both have nearly identical case neck lengths so this is a very direct comparision to case capacity for each case.

    7mm RUM........117 gr
    7mm Allen Mag..127 gr

    Now with both using an OAL length of say 3.700" the AM will offer more capacity advantage because more of the bullet will be out of the case then with the RUM.

    That said, lets figure the AM has 10% more capacity then the RUM. I use 95.0 gr of WC-872 under the 200 gr ULD RBBT for a fireforming load in the 7mm AM(7mm-338 Lapua).

    Basically I would start with 85.0 gr for the 7mm RUM and work up from there.

    Again, this is untested data so use this at your own risk. If I were starting to load the 7mm RUM with this bullet, this is where I would start.

    This may be very conservative but remember that when dealing with a case capacity this size and most importantly a bullet with this weight and baring surface area, it is much better to start low and work up. Again, this may be conservative but I would much rather start low then be suprised until you learn the personality of the barrel and rifle.

    Also, get the bullets well off the lands, at least 0.050" to start with. This will give you a pressure spike cushion in the event you are pushing things a little hard.

    Generally when I start load development from the ground up on a new wildcat, I seat the bullets a full 0.100" off the lands if possible until I establish a standard starting point for that combo of componants.

    Good Shooting!!

    Kirby Allen(50)
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    7RUMloader,

    If your using 104.5 gr as a max load for the 169.5 gr ULDs, I would say that a good starting load for that same bullet would be 10% under that max load. That would be roughtly 94.0 gr for a starting load for the 169.5 gr ULD.

    I would recommend dropping your starting load for the 200 gr to much less then 95.0-96.0 gr to start out at. I would suspect you will top out in the high 90's with the 200 gr ULD. Not a shot at you, just do not want you to get into pressure problems right off the bat. You may not but I would highly recommend starting in the 85.0 gr range with 872 and working up from there just to be on the safe side.

    If you look on the Hodgdon site they list a 94.0 gr starting load for the 175 gr bullets in the RUM with H870 and a max load of 99.0 gr. Now we are dealing with 25 grains more bullet weight and a powder in WC872 that is at times slightly slower but also at times slightly faster then H870 depending on the lot you have.

    Please take another 10% off that starting load just so I can sleep at night /ubbthreads/images/graemlins/grin.gif. I would much rather you find out I am overly conservative and tell me my worries were unfounded then going the other way.

    This is a major increase in weight and baring surface area which greatly increase pressure. Just a suggestion /ubbthreads/images/graemlins/grin.gif!!

    Kirby Allen(50)
     
  10. 7Rumloader

    7Rumloader Well-Known Member

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    Thanks for the heads up and concern fifty! I should have clarified a little more. The 104.5 load was my max summer load and was a little under where I started getting pressure signs of 105 grains. My lot is fairly slow when compared to BMG powder which is slower than 870. I exceeded my 50 BMG load by 5 grains before any pressure signs showed up and then backed down half a grain to stay out of the red during the hot months with high temps. Now it's down in the 70's from high 90's when I was testing those.
    I may back down a couple more grains before starting after your post.

    Thanks again for the concern and heads up since you have more experience with the big RUM cases and wildcats than I do!
     
  11. budlight

    budlight Well-Known Member

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    I've been working on a 30-378 which has some of the powder requirements when using 220 - 240 grain bullets.

    At the local gun store I've been debating using H50BMG over my usual retumbo &amp; R-25. When I saw 8700 for 2-3 dollars less a pound. After refreshing my memory on the burn rate chart. I think that 8700 might fill in. They are all worth a try.


    Reloader 22 (Alliant)
    785 (Winchester)
    H450 (Hodgdon)
    Mag Pro (Accurate)
    N165 (Vihtavuori)
    WXR (Winchester)
    7828 (IMR)
    H1000 (Hodgdon)
    SP12 (Vectan)
    PCL 517 (PB Clermont)
    AR2217 (ADI)
    Magnum (Ramshot)
    Reloader 25 (Alliant)
    MRP2 (Norma)
    TU8000 (Vectan)
    AR2225 (ADI)
    Retumbo (Hodgdon)
    W785 (Winchester)
    H870 (Hodgdon)
    AR2218 (ADI)
    B-12.7 (Somchem)
    N170 (Vihtavuori)
    AR2211 (ADI)
    8700 (Accurate)
    24N41 (Vihtavuori)
    W870 (Winchester)
    50 BMG (Hodgdon)
    H5010 (Hodgdon)
    PCL 513 (PB Clermont)
    SP13 (Vectan)
    20N29 (Vihtavuori
     
  12. davewilson

    davewilson Well-Known Member

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    thanks 50, just curious as to what the WC stands for in the designation WC872 ?
     
  13. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Budlight,

    I have used lots of AA8700 that were as fast burning as Retumbo and others that were as slow as H870. This powder is sensitive to temp changes so keep that in mind. Used correctly, it would be a good choice for the big 30 cal Wby.

    You can get WC872 for $40 per 8 lbs though and its significantly slower then 8700!!!

    Kirby Allen(50)
     
  14. davewilson

    davewilson Well-Known Member

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    just bought some 872 from patsreloading.com for 36/8 lb. get 48 lb and he'll drop the $20 haz mat fee.

    what's the WC stand for?