How to build a 338 Norma

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by darrindlh, Dec 6, 2009.

  1. darrindlh

    darrindlh Well-Known Member

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    What do I need to build a 338 Norma . Will a normal magnum bolt work . Would love your opinions

    Darrin
     
  2. J E Custom

    J E Custom Well-Known Member

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    Darrin.

    I read somewhere that Norma was designing a new 338 and would not be using the 300NM
    as a parent case.

    If this is true, you will have to find out the case head diameter of the 338 NM and refer to the
    Gunsmith section of Long Range Hunting and look under bolt face diameters and com pair with
    the Magnum bolt face of other cases,(534 Dia. is avg.).

    Once you get the diameter if you are not sure just ask and I or some of the other members
    will respond.

    J E CUSTOM
     

  3. geargrinder

    geargrinder Well-Known Member

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    It has the larger case head diameter. It's same as the 338 Lapua or the big Weatherby's.
     
  4. darrindlh

    darrindlh Well-Known Member

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    The reason I am so interested is because Norma makes brass for the 338 Norma . It is avaliable now. So it seems that it would be more reliable to reload and less work. According to zoom other threads the norma is only 50 to 100 fps less than the lapua mag. It seems it would be better for me since I am on a budget.

    Darrin
     
    Last edited: Dec 6, 2009
  5. darrindlh

    darrindlh Well-Known Member

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    On wikipedia the base diameter is .585 for the 338 Norma only .045 larger than a 300 rum. I guess I don't understand why I can't build a 338 Norma off a 300 wm donor rifle when I can build a 338 edge off the 300 wm bolt.
    Darrin
     
  6. kiwi3006

    kiwi3006 Well-Known Member

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    The 338 edge has the same case head diameter as the 300 wm. Remington gave the 300 Ultra the normal magnum case head so that it would work in a normal magnum rifle with less tooling needed. I think it is called a rebated rim or something like that.

    The bolt head of a 300 wm would need to be opened up to accept the larger case head of the 338 norma/lapua type cartridge.
    Some gunsmiths will open up a Rem 700 action others won't. I think the ones that will use the blued receiver, not the stainless as the blued receiver is stronger.
    Otherwise you will probably need to go to a custom receiver.

    Stu.
     
  7. bigngreen

    bigngreen Well-Known Member

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    I think the only problem is going to a larger cartridge is the thrust on the bolt. The pressure isn't running higher than a RUM or WSM but that same pressure has more surface area to work on thus more thrust. Of the 338NM write up's I have read most have been built in shorter barrels and getting near 338LM results so in my mind :rolleyes: the 338 LM and NM are ballistic twins only the NM will function better in a standard sized action because of lenght.
    Hopefully some one will read this thread who can do the math on the bolt thrust of a 338LM vs. a 338RUM. I have seen it but can't recall the thread.
     
  8. darrindlh

    darrindlh Well-Known Member

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    So I am asuming that the 338 edge does not have the same bolt thrust as the 338 Norma mag . What is bolt thrust? Is that recoil on the bolt?
    Darrin
     
  9. bigngreen

    bigngreen Well-Known Member

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    I went through a bunch of threads and could not find the math, there are a lot of guys doing these large 338's on Rem 700 of Savage target action but you will find a large amount of guys that won't touch it. Most of what starts as a guy wanting to do the 338 LM or NM ends in them going with a 338 EDGE or RUM.
    The Savage 110 coming out in a 338LM has me all worked up also but more to take the LM barrel of and screw on a NM barrel to gain bullet seating space for a repeater with longer Berger bullets that will some day magically drop from the sky. But a lot of guys say there is not enough gain over the RUM.
    I believe bolt thrust is like a hydraulic cylinder, you can run the same pressure but increasing the surface area gives you more thrust or lifting capability.
    Hopefully someone will do the math for you before I over think something again :D
     
  10. darrindlh

    darrindlh Well-Known Member

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    Is it worth the trouble? I can have an edge built for $500. But I liked the fact that I could buy factory Norma brass for the 338 Norma. And if I had an edge built I would have to open up the 300 rum brass myself. Just a thought
    Darrin
     
  11. kiwi3006

    kiwi3006 Well-Known Member

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  12. J E Custom

    J E Custom Well-Known Member

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    If the new Norma 338 is down on velocity of the Lapua then the easy way to go would be the
    338 rum. (Not a wild cat, ballisticly a little faster than the Lapua loaded to the same pressure,
    has a standard magnum case head that would fit the bolt face of any magnum (.534 dia.).

    This also means that you can use a standard Remington,Winchester or other action and
    save money for other purchases.

    And to explain the thrust issue+ If a bolt face has 1 square inch of surface and the load
    produces 60,000 lbs/sq in then the bolt sees 60,000 pounds of force. If the same pressure
    is applied to a bolt face that has 1.500 square inches then the bolt sees 90,000 lbs of force.

    This load Is transferred to the bolt locking lugs and with a safety factor of 2 to 1 this reduces
    the factor by 50 %. so keeping the bolt face as small as possible is important.

    The Rum will hold 4 to5 more grains of powder than the Lapua and the Edge will hold 3 to 5
    more than the 338 RUM.

    So the choice is yours. The cheapest to build between the 338 Lapua, 338 Norma, 338 RUM
    and the 338 Edge would be the 338 RUM, (Not a wildcat,factory ammo, no modifications to
    the action and correct head stamp of brass). the most expensive but one of my favorites
    would be the 30/338 lapua Improved. great brass, larger action and bolt face ,expensive
    brass. Custom dies,custom reamers,fire formed brass .

    My Elk rifle is a 338 rum and it is good for 1500 ft/lbs beyond 1100 yards the limit of my
    ability at 68 years of age on big game. (Except hogs have no limits).

    J E CUSTOM
     
  13. darrindlh

    darrindlh Well-Known Member

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    Not having a headstamp on the caseing would not be a problem. I just want a rifle that I can push to 2k on steel targets. I am a long way away from that but with practice it will be doable .
    Darrin
     
  14. J E Custom

    J E Custom Well-Known Member

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    Darrin. any of the big 30s will do that and the 338 will be better for wind bucking.

    For paper or steel a 308 is capable of shooting 2,000yard Creedmoor matches in the hands of
    a good shooter but error becomes magnified so the use of a big magnum really helps. the
    British used the old 303 for the creedmoor matches for years and did well. the first one I shot
    I was using a 7 Rem Mag and placed first in my class.

    J E CUSTOM