300rum or 338rum

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Screwey1, Aug 23, 2014.

  1. Screwey1

    Screwey1 Well-Known Member

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    I have a 300 ultra mag that I believe is due for a new barrel.
    I struggled with this question when I first purchased my 300. 300 or 338 Lapua. Now that I had decided on the 300 back then, some of my perspectives have changed a bit, but the question is no less easily decided. This will be an elk rifle looking to reach 1000 yards if necessary, but want still to be as close as I can. 338 Lapua is out because I want to rebarrel, not reface bolt. 338 Rem ultra has the same bolt face, so no need to open the bolt face. Action needs no work.
    I have a lot of 300 RUM brass and bullets.....this also plays somewhat into my decision. Does anyone know if you can take 300 brass and resize to 338 ultra?
    This knowledge will also help in my decision.
    Any opinions on caliber choice are also welcome.

    Thanks in advance!
     
  2. J E Custom

    J E Custom Well-Known Member

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    The 338 RUM will work great on Elk to about 1200 yards.

    There is another option that you might think about, the 338 EDGE (It is simply a 300 RUM necked up
    to 338. IT has more powder capacity than the 338 RUM and If you already have lots of 300 RUM brass all you need to do is anneal it, size it and load it.

    It will function without any changes to your action and magazine.

    There is also a 338 EDGE AI for even more powder capacity and velocity, with no changes to the action and mag.

    Just a thought

    J E CUSTOM
     

  3. jfseaman

    jfseaman Well-Known Member

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    First part of your questions: Can I size down 300RUM to 338RUM, I am sure of it but have not done it. Is it worth the work?

    So IIWM (if it were me) and of course it was. I'd go with a 338/300 RUM aka 338 Edge. No action modifications. Just neck up your brass.

    If you have a R700 type action, a Wyatts box that will extend your COAL. 3.75" is easy, 4.0" requires a little machining/gunsmithing.

    Load work up seems easy.

    I don't know if I just got lucky but my "finger in the wind" starting load (not really) cloverleafs every time out. I made 700 yards on target with the first 20 rounds with fouler/break in bullets. I'm not going fast yet but I'm accuracy above speed. Last outing, just held for wind and put a mark on the 400y stop sign target. Used that mark to change hold for a dead center hit on same. All that with Hornady 285 HPBT 2nds, sorted by weight and ogive.
     
  4. jfseaman

    jfseaman Well-Known Member

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    J E,

    What are the dimentions of an Edge AI?
     
  5. Screwey1

    Screwey1 Well-Known Member

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    What would the COAL on a 338-300 RUM need to be with say a 300 gr berger hunting vld?
     
  6. J E Custom

    J E Custom Well-Known Member

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    Mag length will determine the coal, (Unless you want to single load)but it will be the same as
    the 300 rum otherwise.

    The EDGE AI has a little less body taper and a 40o shoulder increasing the capacity 4 to 6 grains.

    The reamer manufacture will have a drawing with the dimensions on there reamer. (This is not a SAMME cartridge).

    J E CUSTOM
     
  7. Screwey1

    Screwey1 Well-Known Member

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    Sooooo, the bullet jump could then be mostly controlled when the barrel chamber is cut, meaning seat bullet deeper in the case? I saw something elsewhere that had COAL around 3.9, my mag is only 3.7 tight.
    With the Edge AI could I still use my 300 brass which has only a 30 degree shoulder?
    Am very interested in the Edge as long as I can make it fit using magazine.
    Do you know of a smith that would chamber in the edge? My current smith does not have this chambering listed. Maybe I can talk him into it, but I'd be more comfortable with someone that has done it.
     
  8. Screwey1

    Screwey1 Well-Known Member

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    Are you single loading or mag fed? What did your COAL end up?
     
  9. J E Custom

    J E Custom Well-Known Member

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    You could buy an extended mag if you wanted to add a little, But the EDGE does fine with magazine
    length loads.

    I would recommend seating the bullets to mag length also.

    If your smith doesn't have a 338 EDGE reamer you can order it your self and keep it or sell it when he is done. It also uses the same head space gauge as the 300 RUM and he should have one of those and should have no problems chambering the EDGE.

    J E CUSTOM
     
  10. Edd

    Edd Well-Known Member

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    Using a 300 gr Berger bullet in a 338-300 RUM and a cartridge OAL of 3.70" will put the front of the bullets bearing surface about an eight of an inch down in the case neck. That means the base of the bullet will be almost an inch deep in the case. That doesn't seem like a good setup to me.
     
  11. bigngreen

    bigngreen Well-Known Member

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    I've been just sticking to the 338 RUM, the standard reamer for it from PTG that you can buy from Grizzly works perfect for the 300gr and 250gr Bergers with a Wyatts extended mag and you maintain decent seating without pushing your COAL. All of them I've done will run 2800 ish with the 300 gr and 3100 ish with the 250's, 1000 yard elk is where this combo STARTS to shine and from there is just gets better!
    I like the 338 EDGE with a long COAL because you gain case capacity but on a shorter COAL your really just putting more bullet into the case and defeating the purpose of more capacity.
    You can push 300 RUM back to 338 RUM without much problem, if you size up any used 300 RUM to 338 you need to anneal first.
     
  12. jfseaman

    jfseaman Well-Known Member

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    Mag fed at 3.75"

    I'm in the "it shoots so don't mess with it" mode.
     
  13. J E Custom

    J E Custom Well-Known Member

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    It is not a good set up when the front of the bearing surface is seated is the neck. Some bullet cartridge combinations have to be loaded singly and/or must use a very long action and mag box.

    Some actions are just not suited for the heavy, Secant ojive bullets (Like the 338 300 grain Berger)
    but fortunately there are other very fine bullets available that will work without single loading.

    As to how deep a bullet can be seated into a case, It is most desirable to seat the bullet body flush with the base of the neck to optimize powder capacity, but not a must. Most of the very large cartridges have well over the capacity needed to reach max powder charges and the infringement
    of the bullet into the case body causes no lose in accuracy or consistency and as long as the case density is more than 90% the issue is non existent.

    Longer actions can be found if this is a problem(Seating a bullet longer than the mag length). Or you can have a round that is single loaded and have other mag length rounds in the mag for follow up shots if needed.

    IMO, You don't have to seat bullets long to get accuracy or buy extended mags or actions for longer loadings. It is a matter of ease or convenience.

    I believe in the Keep it simple philosophy and it has served me well. so why complicate things when loading for velocity and accuracy.

    Just My Opinion

    J E CUSTOM
     
  14. AZShooter

    AZShooter Well-Known Member

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    Screwy1,

    Addressing your original question 300 RUM or 338 RUM. Bryan Litz has a chapter in the rear of his newest book where he discusses the performance of the 300 Win mag with the 230 gr OTM vs the 338 Lapua which is pretty much the ballistic twin to the 338 RUM. He is comparing them for sniper shots out to 1500 yds.

    He said out to 1500 yds the 300 win mag with 230 Bergers beats the 338 Lapua with all bullets except the 300 gr Berger hybrid.

    Based on that information the 300 RUM will obviously be superior to the 300 win mag performance. If you switch to the 230 match target hybrid with its higher BC you can gain even more.

    I am not going to detract from the performance of a 300 gr hybrid on LR elk from a 338 RUM or the 338 Edge. Just suggesting that the 300 RUM with either 230 gr hybrid will certainly get the job done as well. Recoil will be low enough that a brake isn't necessary. (My 8 1/2 lb 300 RUM with 230s @ 2975 is manageable without a brake) If you crunch the numbers to useful hunting distances the two chamberings are very close in trajectories and wind drift. I will admit the 338 will have more energy with the heavier bullet.

    You already have the components dies bullets etc why switch when the gain not significant? Of course there is the appeal of a new chambering. Your choice.