Powder selection for RUMS

Discussion in 'Reloading' started by sambo3006, Jun 8, 2006.

  1. sambo3006

    sambo3006 Well-Known Member

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    I got some responses for powder selection for the 7RUM a week or so ago. I have a 338RUM also. Am I correct in assuming that slower powders would work better in the 7RUM than the 338RUM due to the smaller hole in a big case?
    I loaded up 102gr of Retumbo behind a moly 225gr AB in my 338RUM and was hearing some powder crunching when I seated the bullet (OAL to fit in the mag). This load is below max and avg velocity was 3006 fps from a 26" barrel. I would like to hit 3100 fps but don't like crunching powder. I bought some H1000 which is a little faster and looks to generate the same pressure with a few grains less powder. I'm thinking that the H1000 would work better in the 338RUM and the Retumbo would work better in the 7RUM--I'm going to use 150 gr bullets. What say you?
     
  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Sambo3006,

    Here are the burn rate of powders I recommend to my customers for each of the RUMS. These are general recommendations meaning any powder with similiar burn rates will perform equally as well.

    7mm and 300 RUM
    H-1000
    RL-25
    Retumbo

    338 RUM
    H-4831
    Rl-22

    375 RUM
    H4350
    H4831

    These generally get about all the performance you can get out of these rounds with a good level of load density.

    Retumbo is pretty slow for your 338 RUM, especially with a 225 gr pill. Look at some Rl-22 and see what happens. I suspect you will be suprised at the performance level you get and load densities will be a bit more powder friendly when seating bullets.

    Even H-1000 is a bit on the slow side. With 250 and 300 gr pills it would work well but not a 225.

    Retumbo seems to be one of "THE" powders for the 7mm RUM. 300 RUM as well.

    Kirby Allen(50)
     

  3. sambo3006

    sambo3006 Well-Known Member

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    Thanks Kirby. This is exactly the type of info I was looking for. I have both RL 22 and IMR 7828 on hand. The max load on the IMR website for 225gr 7828 is 92 gr. I believe this is with the 225gr partition, so it may be a little different with the AB. RL 22 should be similar. I'll back off some and chrono test my way up while observing for pressure signs.
    Thanks again,
    Sam
     
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Should work well, keep us posted with the results!!

    Kirby Allen(50)
     
  5. goodgrouper

    goodgrouper Well-Known Member

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    I agree with Kirby. RL22 works great in the 338 ultra mag and produces top velocities and usually top accuracy as well. Nosler number 5 shows faster velos with RL25 and the 225 grain bullets but I have yet to see RL25 shoot faster than RL22.

    You could also burn RL22 in a 7 ultra in a pinch but your loading densities would be on the low side.