7mm Ultra Powder Choice

Discussion in 'Reloading' started by Earl Fouraker, May 28, 2008.

  1. Earl Fouraker

    Earl Fouraker Well-Known Member

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    My 7 ultra barrel should be here in the next couple of weeks and I'm needing to go ahead and order some powder. I was wondering what powder everyone was having success with and what velocity you where getting. My barrel is 30" and I plan on shooting the 162-180 class bullets.
    Thanks
     
  2. linksmechanic

    linksmechanic Well-Known Member

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    I would try retumbo.
     

  3. Willys46

    Willys46 Well-Known Member

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    Retumbo or H1000

    I have had good luck with Retumbo, but in a 26 inche barrel I think it might me a tad slow. With and extra 4 inches I would think it would work great. I am running 93gr behind a 160 accubond.

    Willys
     
  4. sdeviation

    sdeviation Well-Known Member

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    i have only used retumbo in mine 26 inch tube.... 88 and 92 worked good with a 168 hpbt
     
  5. steve smith

    steve smith Well-Known Member

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    I would have to say if your going to the trouble of putting a 30" barrel on the rifle, that you are probably looking for close to maximum velocities with those heavy bullets. In that case i would recomend that you look to the slower ball powders like AA8700, US 869, or some surplus WC 872 (20mm powder, or 860 (50 bmg powder).

    Now I was using AA8700 and 872 in my 270-300 Rum (another .007" and it is a 7mm rum), and found that they gave velocities greater than that of powders like H1000 or Re 25 with less pressure. Of course my rifle also had a 30" barrel, but the velocities i was getting were
    135 MK 3750fps (working load, 5-6 fireings per case)
    140 SST 3715fps (Absolute max 3-4 fireings per case)
    150 SST 3650fps (Best load, about 10 fireings before case necks split)
    Now you can extrapolate that using a 168gr bullet, the velocity would probably fall in the 3450-3550 fps neiborhood and the 180 close to 3300-3400 fps.

    Yah, I know the loading manuals won't show velocities that high, but just remember the barrels they use in their test are usualy only 24-26" long, and that extra 4-6" of barrel can make a world of difference when talking about a fairly small bore like a .277/.284, especialy when your using heavy for caliber bullets.
     
  6. Peters

    Peters Member

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    94gr of retumbo 26in barrel got me 3350fps
     
  7. Earl Fouraker

    Earl Fouraker Well-Known Member

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    Peters,

    What grain bullet were you getting 3350 with. Also barrel length/pressure signs?
     
  8. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    THere are alot of GOOD powders that will work in the 7mm RUM.

    For conventional weight bullets, Retumbo is about as good as it gets and very consistant over temp changes and pretty good with elevation changes as well.

    If your using the heavier bullets, the slow burning ball powders also work very well such as AA8700, old H870, H-US869 and the surplus powders such as WC872 also work great. You will get very good velocity, great load densities and generally very consistant velocities with these powders. Sounds like win-win but not always.

    These powders will add 5 to 10 gr to the powder charges you will be using compared to stick powders. SO what? well, this increase recoil, not an issue if your using a brake but if not you can feel the difference in recoil, especially in a sporter weight rifle.

    Also, these powders do not burn very clean, in fact they are quite dirty burning. Even if you can get enough powder in the case to get up to around 65,000 psi, they still leave MUCH more carbon fouling in the bore compared to modern stick powders.

    Also, if you will be shooting and hunting in varying elevations of in varying temperatures, you will see a much more significant change in POI with ball powders compared to stick powders.

    Do not read this as me being down on these ball powders, I am certainly not in any way but you need to realize their characteristics to get the best use out of them. I use them alot in my larger capacity wildcats and they work great. You need to remove the carbon fouling every 25-30 shots down the barrel and if you want to load to full pressure, you will need a cool and hot temp load for summer and winter. I generally just load to a safe load in hot temps and then when its cold, test the rifle to see what velocity its getting and develope my drops off that so I do not have to play with different loads, 100 fps change does not make any difference as long as you have your drops corrected for the velocity drop.

    If it were me, I would probably start with Retumbo and see how it performed for you, if that did not work up to your performance specs I there are other options but those other options come with other issues.

    Kirby Allen(50)
     
  9. Peters

    Peters Member

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    Earl,
    I have a rem sendero with a 26in bb with a brake. I was using 160 gr accubonds no pressure signs but think that load is about max before problems.