338 Lapua Mag or 338 RUM

Discussion in 'Long Range Hunting & Shooting' started by John Sanner, Nov 15, 2010.

  1. John Sanner

    John Sanner Well-Known Member

    Messages:
    74
    Joined:
    Jul 4, 2009
    Well Ive decided to do another build and was wanting something in a 338 caliber. I cant decide between the 338 Lapua or the 338 RUM. I know the brass will be cheaper for the RUM but Ive heard that the 338 Lapua mag is more accurate. Please help me decide.
     
  2. liltank

    liltank Well-Known Member

    Messages:
    4,158
    Joined:
    Nov 3, 2008
    6 of one, and half dozen of the other really. They use pretty much the same amount of powder. Both can be made to be very accurate. So I would say your safe either direction. I shoot a Lapua occasionally and feel due to the brass quality, you can get a little edge toward velocity verses the RUM. But head to head you really shouldn't see much difference.

    Tank
     
  3. B23

    B23 Well-Known Member

    Messages:
    1,118
    Joined:
    Oct 30, 2008
    I'm no pro, just your average joe shooter so take this for what you will.

    I don't think one is anymore or less accurate than the other. BUT, if you are going custom anyway, I would never do a 338 Lapua that wasn't one of the "improved" versions. IMO, an improved 338 Lapua is well worth any extra fuss you may think it involves.

    If you have Kirby Allen build you one of his 338AX you not only get your dies with the build but you can buy fireformed 338AX (338 Lapua improved) brass from him. If you want to fireform your own that works too because the standard 338Lapua loads will easily shoot M.O.A. they just won't be quite as fast.

    For me, a 338 Lapua Improved would be a no brainer and kinda the best of both worlds because it would still shoot factory 338 Lapua ammo very well.
     
  4. Long Time Long Ranger

    Long Time Long Ranger Well-Known Member

    Messages:
    2,612
    Joined:
    Mar 12, 2002
    Both are equally accurate. I just pulled up data for two 338 RUM's and two 338 Lapuas with 30" barrels that I built and tested at my shop. All four had excellent accuracy to about 2830 fps with the 300 smk (varied slightly between guns). I have been able to run velocities just a little faster overall with the Lapua probably because the lapua brass would load to higher pressures. But basically the 338 RUM, 338-300 RUM or edge on here and 338 Lapua are identical in accuracy and performance. Overall if you want to push them to the max I have been able to get just a little more velocity out of the 338 Lapua than the other two probably because the Lapua brass will take higher pressures. 90% of these are going to max out with best accuracy between 2750-2850 fps.

    The Lapua may be more expensive to build because of the action it requires and will be more expensive to shoot with the brass. I agree with others that I would consider the 338 Lapua imp at the minimum if you are doing a custom action. The ultramags are great if you have a donor standard magnum action to save some cash but if you are going custom then look for more bang for your buck. Improved versions of the 338-378 wby case and A'square's 338 Excalibur can give you 200-300 fps over the standard Lapua and ultramag based cartridges easily pushing the 300 smk well over 3000 fps. All are accurate and fun to shoot. A 300 smk at 3100 fps is way fun to shoot at extreme long range over 1000 yards.
     
  5. GNERGY

    GNERGY Guest

  6. djbwow2008

    djbwow2008 Well-Known Member

    Messages:
    92
    Joined:
    Aug 30, 2008
    I agree with B23 and I put my money where my mouth is . I am getting real close to receiving my 338AX from Kirby. Never really considered the 338 Rum. For me its the 338 Edge over the Rum in a Custom build. Nothing wrong with the 338 Rum its just the 338 Edge is better in every way IMO. The quality of brass for the 338 Lapua puts it at the top of my list improved or not. Accuracy will be to close to tell if you use a good Smith.

    Dan
     
  7. djbwow2008

    djbwow2008 Well-Known Member

    Messages:
    92
    Joined:
    Aug 30, 2008
    Just wanted to add if you find that building a 338 Lapua/or improved puts you over your budget due to the higher cost of action required for the Lapua sized bolt face, contact Nate at Straight Shot Gunsmithing. He has a Defiance Machine action built to his specs that is super sweet. He uses it on most of his builds. I just decided to have him build me a gun on this action. Its priced right inline with most the actions you would use for a standard magnum build and its top notch. You would be hard pressed to find a better Smith than Nate and he is a great Guy to deal with.

    Dan
     
  8. B23

    B23 Well-Known Member

    Messages:
    1,118
    Joined:
    Oct 30, 2008
    I've always been a big fan of Glen Harrison's receivers. Others must think so too because he seems to be making alot of "personalized" receivers for different smiths.

    Doubt you could ever go wrong with one of his products.