Whats the Difference between the 338x408 & 338x416

Discussion in 'General Discussion' started by wildcat, Oct 9, 2006.

  1. wildcat

    wildcat Well-Known Member

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    Hey guys, what's the difference between the 338x408 Cheytac and the 338x416 Rigby. Are they the same when it comes to performance, or is one better than the other. I am curious, and would like to get your guys take on the issue. I am having a 338 Allen Mag built, so I've become very interested in these high power 338 monsters.

    Wildcat
     
  2. triggerfifty

    triggerfifty Well-Known Member

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    On the positive, the 338/408 is going to be much faster on velocity. You pay for that in the shape of the trajectory, and at ranges past the maximum ordinate range, or 60% of the total range, your fall angle is going to be steeper. This is a "danger space" dimension that gets shorter as your fall angle is steeper. What this all boils down to is, YOU HAVE TO BE MUCH MORE ACCURATE on your range to target. As that target gets smaller, the MORE accurate the range has to be.

    The gun with a velocity in the 3000 fps range will have a long range advantage in this case. Velocity does not gain you much supersonic range, it only gains you a "cheat" in the trajectory BEFORE maximum ordinate. That's where guys are referring to when they say "it shoots flatter". It only shoots flatter in the "rising branch" of the trajectory. If that's where you plan to shoot, then you are fine. With rifle of 2200 yards of supersonic range, that "rising branch" is about 1400 yards. Then it becomes falling branch, which is where the danger space dimension is critical. This is kind of a spinoff discussion from before about guns with very high velocities having their projectiles slow down faster. That points was missed in that guys focused on a projectile actually "passing" another that is launched slower, it doesn't work that way.

    3000 fps has an advantage in that it doesn't burn out barrels. A .768 BC bullet is only supersonic to "x" yards, changing he velocity only changes that supersonic range from 2900 fps to 3400 fps gives you a supersonic range gain of 21% (NOT using a standard G1 ballistic co-efficient, but real data). That's a good gain, BUT, the danger space dimension is much shorter at 2300 yards and 3400 fps, than it is at 2300 yards and a muzzle launch speed of 2900 fps.

    It gets much deeper than this though. Add in the additional cost of powder, brass, and barrel wear, the high velocity guns are $$$ demanding.

    Just my ,.02
     

  3. Black Diamond 408

    Black Diamond 408 Well-Known Member

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    Wildcat,
    The 338-416 rigby or improved versions are very nice cartridges, it is basicly the same as a 338-378wby imp case, same powder capacity. The rigby case has one big advantage over the WBY case, no belt to worry about and the brass seems to be better. The 338 Lapua is also based on the 416 Rigby case, only shortened. You can expect velocities around 2900fps in standard length bbls, 300grn bullets. You allready know about the 338-408 guns and what they will do. You can build lighter rifles using the Rigby brass, it dont take the oversized actions and bbls like the 408 class of rifles.

    Dave
     
  4. lerch

    lerch <strong>SPONSOR</strong>

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    [ QUOTE ]
    What this all boils down to is, YOU HAVE TO BE MUCH MORE ACCURATE on your range to target. As that target gets smaller, the MORE accurate the range has to be.


    [/ QUOTE ]

    Sure seems to me that if i want to hit a chuck, gong, person or beer can at ultra long range I would want to have a EXTREMELY accurate range anyway.
     
  5. wildcat

    wildcat Well-Known Member

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    Thanks guys, and good info!!

    Wildcat
     
  6. davewilson

    davewilson Well-Known Member

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    BD408, when you say can be built on smaller actions, are you referring to a 700? i know some go with a 700 with the 338/378, but don't known about the rigby.
     
  7. Black Diamond 408

    Black Diamond 408 Well-Known Member

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    Dave,

    I think most use the large Sako type actions or the CZ actions for the Rigby cases. Not to mention the customs out there. I used the Bauska actions for most of the ones i built. Large Mauser type.

    Dave