choosing ammo

Discussion in 'Large-Bore/Small-Bore Rifle/Shotgun' started by warpig, Feb 24, 2003.

  1. warpig

    warpig Guest

    Santos
    Member
    Posts: 1
    (12/20/02 9:07:01 pm)
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    I need a lesson about ballistics relations to bullet grain wt. What is the best wt to use? I shoot a 7 mm rem mag. I have been using 150 grain remington. I have been looking at ballistics charts, I thought the higher the weight the higher the velocity/flatter trajectory but that does not seem to always be the case.

    Thanks


    shooter22
    *TFF Staff*
    Posts: 1767
    (12/20/02 11:46:30 pm)
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    Welcome Santos.


    Quote:
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    I thought the higher the weight the higher the velocity/flatter trajectory
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    This is exactly the opposite. The lighter the bullet, the higher the speed(velocity). The smaller bullets will have a better(flatter) trajectory than higher weight bullets.

    The heavier the bullet, the more it retaines energy when it hits a target

    Finding a balance between, Velocity/speed, and energy retention/knock down power, is the ideal plan.



    Hey, Bin Laden, our women can kick you butt!






    Santos
    Member
    Posts: 2
    (12/24/02 3:13:25 pm)
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    So the grain weight that is labeled on a box of shells is referring to the wt of the projectile. Not the amount of powder used in the bullet.

    Thanks

    kdub01
    *TFF Senior Staff*
    Posts: 1640
    (12/24/02 3:28:31 pm)
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    Yes - the grain weight marked on the box is the projectile weight.

    Exterior ballistics is a world unto itself. You need to get a reloading manual published by the bullet makers or powder manufacturers to get an idea of ballistics and the tables.

    While it is true the lighter weight bullets in a caliber will have faster initial velocity and a flatter trajectory, the same light weight works against it due to less sectional density and ballistic coefficients. This means the air resistance slows a light weight bullet down faster than it does for a heavier more efficient bullet.

    A pointed projectile has less air resistance than a blunt tipped projectile. A boattail bullet has greater coefficients than a flat based bullet.

    Gravity affects all bullets as soon as they leave the muzzle. How much drop is determined by the speed the projectile is travelling, the B.C. of the bullet and the density of the air.

    'Nuff said - any more will be getting into detailed info that's best looked up and read from the manuals.

    Your 7mm Rem Mag will shoot from 140 gr to 175 gr bullets with aplomb - just means you select the bullet for the job at hand. 140's and 150's are great for antelope/mule deer sized animals. the 160's and 175's are equally good for mule deer to elk/moose sized critters.
    "Keep Off The Ridgeline"
     
  2. Dead.Eye.Steve

    Dead.Eye.Steve New Member

    Joined:
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    Messages:
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    When selecting bullet weight, I first determine the average range I expect to shoot Big Game at - i.e. 200 yards.

    Next, using the manufacture's ballistic table, look down the Muzzle ENERGY (ME) column for 200 yards and give serious consideration to the weight of bullet with the highest downrange energy.

    In the 7mm Mag, usually 175 grain carries the most wallup, but a smaller bullet will do the job too, as this caliber is overkill for many animals.

    Good luck!
     

  3. stash247

    stash247 New Member

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    Kilimajaro Bell killed over 1000 Elephant with a 7mm mauser (Actually, 275 Rigby-same cartrige), so it's not like you need a whole lot of help on energy, to kill anything on earth.
    Bullet placement, and on occasion, penetration, are the keys
    In North America, everything is "thin Skinned", so the answer is what YOUR rifle shoots best, as in most accurately.
    A Nosler 140 will run out of gas far after I run out of eyesight, even in a 7mm Mauser, but it is the most consistant hunting bullet I've ever used.
    That help???
     
  4. 45Smashemflat

    45Smashemflat Active Member

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    Last bit of advice - find out the rate of twist in your barrel - faster twist for heavier bullets. You may find, as I did, that you rifle likes lights stuff over heavier stuff, esp if you don't reload.

    (Kimber 84M - likes 165gr game kings, hates any 180gr factory load - 1in12 rate of twist - for example.)