7 lrm ballistics.?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Long Range, Jun 13, 2013.

  1. Long Range

    Long Range Well-Known Member

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    I have done a search looking for some numbers on the 7 Lrm but haven't found much on it. I know it's pretty new but I figure there are enough of them out there I could get some ballistics on it. I've read on Gun Works web page that it will run the 180 @3100 under 72gr of H1000 in 26 inch tube. That seems like its just a hair hotter than a 7 Rmag.

    I've would like to hear from someone that has one what the case capacity is and some known velocities are and what barrel length you are running to achieve them. I'm gonna build a big 7 and its a toss up on weather to build a 7 lrm or 7x300 win mag or version of.

    I have most everything I need just need to pick a direction a go. One thing I would like to know is I have a 1-8/5 twist barrel just wondering ho much this would slow either on of them down and what length to run. It's a 31 inch blank.
     
  2. mitch260

    mitch260 Well-Known Member

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    I don't have one, but one benefit of the LRM is there isn't a belt. One downside is limited availiblity of brass.
     

  3. JARHEAD1371

    JARHEAD1371 Well-Known Member

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    Another option is a 7/300 Norma Mag. You could even step up to a 190 gr Matrix or 195 gr Hybrid. That will be an amazing combo for anything moose sized and smaller. I'm torn between the 7 LRM and 7/300 NM for my next build. I'd like to know what the LRM can do with the 190 Matrix out of a 28" barrel...
     
  4. elmerdeer

    elmerdeer Well-Known Member

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    I have a custom in 7mm Dakota 25" barrel 8.5twist Krieger barrel, I shoot the 190gr Matrix bullets and
    the 180 Hybrids both with H1000 and with retumbo and I get 2960-2975 avg for the 190's and
    3010 for the 180 hybrids. All this with between 72-74.5 grains of powder so I am assuming that
    the 7LRM has almost Identical case capacity as the 7dakota.
    Hope this helps

    Elmer
     
  5. AZShooter

    AZShooter Well-Known Member

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    I have a 29 1/2" lilja 6 groove 1 in 9 twist. The case is the 375 Ruger necked down to 7mm without any changes to shoulder. The 7 LRM has the shoulder moved to lengthen neck so its capacity will be slightly less.

    180 gr Berger hybrid target is going 3175 fps with 83 gr of RL-33.
     
  6. Long Range

    Long Range Well-Known Member

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    Any updates on the 7lrm?
     
  7. elkaholic

    elkaholic Well-Known Member

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    Those must be fairly mild loads? I'm pretty sure the Dakota holds 6-8 grains more than the LRM.......Rich
     
  8. elkaholic

    elkaholic Well-Known Member

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    I just checked the H2o capacity on a new 7 LRM and it holds 87.4 grs. filled to top of neck. I don't have a Dakota case but I think they hold around 95 grs.?.........Rich
     
  9. Long Range

    Long Range Well-Known Member

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    Will the Dakota rim fit into a standard mag bolt? I have all the parts together for a new build and Im down to the 7lrm or 7mm Dakota. I was going to go with just a simple 7x300win but I want fit in to a aics mag without reducing charge. I'm looking to get the 180 berger to 3100 or just north and the 190 to 3000.

    So between to two which one is the most likely to meet my goal. Assuming I can use the Dakota case as the rim is bigger. I have a barrel that will finish at 30 or shorter.
     
  10. elkaholic

    elkaholic Well-Known Member

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    There is no doubt that the Dakota will reach higher velocities than the LRM but that isn't to say that they both wouldn't reach your goal with a 30" barrel. Dakota brass is probably tougher but also more spendy. The Dakota rim is .013" larger so would probably require opening the bolt face a touch.......Rich
     
  11. elmerdeer

    elmerdeer Well-Known Member

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    Those loads in my gun are very close to max!!! there is no way I would start with any more powder. I have over 1000 rnds down the old barrel (rock creek)and new barrel Krieger, and both
    barrels shoot within 30 fps of each other and that because on is 24" and the the other is 25". The only rnds I have not chronoed are my hunting rnds, so my speeds are on cause I've also verified them out to 1000 yards.
    In my gun, extractor marks would show up with sticky bolt at 75grs of Retumbo and 74.5 grs of H1000.

    Elmer
     
  12. Long Range

    Long Range Well-Known Member

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    From what I've read is the Dakota and the 7lrm brass are both made by Hornady. Some say the 7mm Dakota is norma and some say its Hornady.

    I have a custom BigHorn receiver with a sliding plate extractor. I will measure to see if it will fit. But if not than my decision may be made for me.
     
  13. elkaholic

    elkaholic Well-Known Member

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    I thought Dakota was made by Norma, but I have owned neither so not sure. Your bolt may work as it is......rich
     
  14. elkaholic

    elkaholic Well-Known Member

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    Thanks Elmer! Ya, I was looking at data from longer barrels and not paying attention to load.......Rich