7mm RUM velocity with 180's

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Earl Fouraker, May 1, 2008.

  1. Earl Fouraker

    Earl Fouraker Well-Known Member

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    I'm thinking about getting away from the 338 and building a 7RUM for my new long range thumper. I have a Brand new savage action that failed to sell in the classifieds, so I'm forced to order a new barrel....how terrible.... I've been running the ballistics on both the 180 bergers (BC of .684), and the JLK 180's (BC of .735). My questions are what type of velocity is obtainable out of a 30-31" barrel with these bullets. I'm hoping 3300fps is a possible velocity. I know that my barrel will be toast after about 800-1000 rds. But with the bullets available I think it would be an awesome LR rifle. The JLK's @ 3300 are only dropping 18.1 MOA @1000 with a 100 yd zero with 4.0 minutes of windage with a 10mph crosswind. That's amazing!!...Thanks
     
  2. jwp475

    jwp475 Well-Known Member

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    I believe that you can run arounds 3000 FPS or a bit over with the 180s. Give them a try and let us know..

    What is your barrel lenght, I based my answer on a 26" barrel
     

  3. Midgetsniper

    Midgetsniper Well-Known Member

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    JLK's?

    Im looking for bullets to try, to run through my 7mm RUM when i get it. what are JLK's
    __________________________________________________________
    Lefty's are the normal ones in the shootin world.gun)
     
  4. Earl Fouraker

    Earl Fouraker Well-Known Member

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    The JLK's are a custom made VLD bullet. I think the company is also called swampworks. You can google it and go to their website. I have heard alot of good things about their bullets on 6br.com. Used alot in 1000yd comp. I went ahead and ordered me a 30", #7, 9twist, 3 groove pac-nor today. Should be here in about 8 weeks and then I'll let you know what it will do. The nosler manual shows an STW @ 3047 fps with a 175 out of a 26" barrel. I think with the extra barrel length and the extra powder capacity, 3300 will be obtainable....hopefully.
     
  5. SUNDEVIL

    SUNDEVIL Well-Known Member

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    Im building a 7rum too! Schnieder m40, contour 1/8 twist, 5r, 28". I was hoping to get at least 3200fps. I think it'll be a blast. Moly 180's. Good luck with your build!
     
  6. Brain

    Brain Well-Known Member

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    Somebody should start a 7RUM build thread. I'm building two at the moment. Both using Rem 700 actions and Rock 30" 5r 9-twist AMU contour barrels. On the fence as to whether or not to AI them both or just one to compare.

    I'm hoping for around 3200fps with the 180's. Anything above that will be gravy if ES is low and groups are tight.
     
  7. MagMan

    MagMan Well-Known Member

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    These numbers came out of my log book. All for the 180 Bergers. With a Mike Rock 8.7 5R in 7mm RUM.

    US 869
    99.1=3345
    100.=3367

    Retumbo
    88=3292

    H870
    92=3250

    These are just loads I was using. Not starting loads and not max loads.
     
  8. SUNDEVIL

    SUNDEVIL Well-Known Member

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    How was the accuracy with 869? What was the barrel length? Thanks.
     
  9. WAMBO

    WAMBO Well-Known Member

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    With a minimal amount of testing I was getting 3185 fps with the Berger 180's using 89.5grs of Retumbo out of a 27" Rock 1-9" twist barrel.
    The load was close to max, might have been able to go another grain but didn't see the need.
    Accuracy was acceptable but not outstanding, .75 moa for 3 shots at 1K.
    I definitely will be trying US 869 in the future.

    Wayne aka WAMBO
     
  10. davewilson

    davewilson Well-Known Member

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    mine went 3250 comfortably, could go over 3300 with extractor marks. 99gr of 872 powder, lilja 7T,M 30" barrel. didn't try other powders. i would not use a 3 groove barrel with this amount of overbore and Berger jackets. i have a friend that would dust 168 Bergers with a 9T and 6 grooves. i would recommend a 5R barrel as the minimum number of lands for this combo.
     
  11. MagMan

    MagMan Well-Known Member

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    My barrel was 30".

    Accuracy with US869 wasn't great (MOA). I burned up 2 lbs and still didn't find anything I was happy with. Retumbo was my goto powder.
     
  12. tjonh2001

    tjonh2001 Well-Known Member

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    i know that im not shooting a rum but i am getting 3230 out of my 7mm wsm burning 67grs. im sure that you guys should easily get 3300 out of a RUM
     
  13. Shawn Carlock

    Shawn Carlock Sponsor

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    I have gotton between 3250-3300 with the Berger 180 in the ones I have built out of a 30" hart barrel.
     
  14. Earl Fouraker

    Earl Fouraker Well-Known Member

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    I ordered the 3 groove barrel with the thoughts that the wider lands might slow the throat wear down alittle. The last 4 barrels I have bought have all been 3 groove and they have all been outstanding. They have been in slower rounds like the 6Br, 308, and 338-300. Would you quys go with something different then a 9T 3groove for the 168-180 bullets in a rum? I would not have thought that the 3 groove would be too hard on the bullets. Doesn't Kirby build alot of his 7mm allen mags with a lilja 3 goove? I think 9T will be fine @ the speed I will be pushing the 180's but I'm not really sure. Any info will be great. Thanks