7MM Velocities

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Tumbleweed, Jul 23, 2009.

  1. Tumbleweed

    Tumbleweed Well-Known Member

    Messages:
    452
    Joined:
    Oct 20, 2007
    Hello guys, just looking for a little info. My next long range hunting rifle project will probably be a 7mm STW of a 7mm Rem Ultra. I will most likely run the 168 Berger VLD's exclusively. The barrel will be at least 28", maybe more to get the most efficient burn and velocity potential. What are your velocity experiences running a 28"+ barrel with the 168 VLD's in either caliber? Also have heard the RUM is a barrel burner and loads may have to be reduced as throat wears, if this is true, that won't work. I am basically looking for high velocity in the 7mm caliber to keep that berger at 1800 fps as far out as I can, but I shoot a lot and the barrel will have to last too! Thanks
     
  2. Limbic

    Limbic Well-Known Member

    Messages:
    320
    Joined:
    Jun 26, 2008
    Not exactally what you asked for but here is some info to help you get started.

    My 7mmRem Mag with a 26 inch Shilen shoots the 168 pretty good.

    According to the iPhone Ballist FTE app using the G7 drag model my load keeps 1800ft/lbs out to 1200 yrds. That is a MV of about 3030.

    BTW the drop is 294 inches or 24.5 ft. wow. Not a real bad barrel burner and only about 66 grains of poweder as well.
     

  3. Tumbleweed

    Tumbleweed Well-Known Member

    Messages:
    452
    Joined:
    Oct 20, 2007

    Thanks for the reply limbic! WOW, are you sure that data is correct? JBM shows the 168 at 3,030 with the G7 litz as follows: 1,800 fps should be right at 910 yards and 1,800 ft/lbs at about 585 yards and the drop at 1,200 from a 100 yard zero should be 407.6 inches! Have you shot those kind of distances along with your program to verify it's accuracy? Just curious, thanks!
     
  4. eddybo

    eddybo Well-Known Member

    Messages:
    1,651
    Joined:
    Jan 5, 2007
    Hmmm velocity and longevity.....seem pretty mutually exclusive. I am not sure your going to get what your wanting, gotta be a trade off somewhere. Just get the baddest hotrod you can find and stock up on barrels:)
     
  5. freelunch

    freelunch Active Member

    Messages:
    33
    Joined:
    Jan 4, 2009
    Tumbleweed,
    If I use JBM for where I live at in Colorado at 5000 feet asl, given the above info, then 1800fps and 294 in drop is correct for 1120 yards. So it matters what altitude you live at as well as temperature and pressure used. I guess you live at sea level right on the shoreline (since you used 0 feet for altitude to get 910 yards)? :)
     
    Last edited: Jul 24, 2009
  6. Tumbleweed

    Tumbleweed Well-Known Member

    Messages:
    452
    Joined:
    Oct 20, 2007
    You're Right, I stand corrected! Yes, we are at sea level, guess that high altitute can be a real advantage. The highest we get when elk hunting is about 2,500 feet.
     
  7. 338 bruce

    338 bruce Well-Known Member

    Messages:
    230
    Joined:
    Aug 1, 2008
    7mm tejas (7mm rum improved) 180 gn berger 3400 fps 2500 rounds and counting says the builder. I will be builing one as a switch barrel for my 375 tejas.
     
  8. Tumbleweed

    Tumbleweed Well-Known Member

    Messages:
    452
    Joined:
    Oct 20, 2007
    Wow! I would like to hear a more about this set up.
     
  9. Limbic

    Limbic Well-Known Member

    Messages:
    320
    Joined:
    Jun 26, 2008
    I tried the JBM calculator. I got some pretty different numbers as well. The problems is that regardless of what drag model you use the numbers don't change.

    I know there is a place on the front sheet to pick a model but it doesn't matter.