If I am using 80 grs. of 7828, where should I start with Retumbo ?

Discussion in 'Reloading' started by Marine sniper, Jul 19, 2008.

  1. Marine sniper

    Marine sniper Well-Known Member

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    I am using 80.0 of 7828 in my 300 WBY, at 3000 fps. The load is very accurate, an honest 1/4-1/3 MOA rifle at 300 yards if I do my job. The problem is the load is very hot in my rifle and when the temps climb into the 90 degree range my bolt gets sticky, hard on cases also. My load density is approx 95% with the 7828. I bought a pound of Retumbo and H1000. I figured I would give Retumbo a shot.

    Since it is slower burning can I start at 79 grains of Retumbo and work up from there ?

    Since the rifle likes the 3000 fps area for these bullets (Berger 210) is that the velocity I should shoot for with the other powders ? Is there a possibility Retumbo might get a little more velocity and not loose any accuracy.

    I am going to try some Remington Brass instead of the Weatherby stuff.

    Any tips ?

    Thanks,

    John
     
  2. Iron Worker

    Iron Worker Well-Known Member

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    What don't you like about Weatherby brass?

    reloadernest.com all your questions will be addressed there.According to new Sierra manual RE#25 is the powder you want. 84.8grs is max with 200 gr bullet for a MV of 3,100. Retumbos max is 85.7 for a MV of 3,000.
     

  3. Iron Worker

    Iron Worker Well-Known Member

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  4. Derek M.

    Derek M. Well-Known Member

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    Appears to be a good starting point but if your bullet is at or into the lands, 77 or 78 gr would be a little safer.

    3000 fps is of course a good goal, but the Retumbo may have different nodes at even higher velocities that produce equal accuracy. You just don't know until you try it.

    I always recommend new load development on warmer days if possible so you can find what top end powder charges will be with the bullet seated at or into the lands. Not sure why you want to go from Norma brass to Remington. Isn't that a step in the wrong direction?
     
  5. Marine sniper

    Marine sniper Well-Known Member

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    Thanks, I have a bunch of Virgin Rem brass I was going to try. If it does not produce the results the Weatherby brass produced I will use it for my hunting loads (200 AB's)

    These loads are .020 off the lands.
     
  6. kraky2

    kraky2 Well-Known Member

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    I've played with both 7828 and retumbo a bit in a wby factory riflle with freebore. It's my guess that all being the same you would wind up about 2.0-2.5 grains higher with retumbo. BUT being you are changing brass from wby to rem it's possible that your idea of starting at the same 80 grains is where you might wind up at max. Sooooo....I'd say the advise of starting down near 77-78 and working up is very sound.

    BTW---retumbo shot really good with 200 ab's in my super fussy 300UL.....but 180 tsx's shot even better. Before retumbo rolled along I was about to rebarrel that gun. Now I have confidence in it. Also...retumbo has tested pretty good with temp swings for me but I haven't tried it in really hot weather....just 20 degrees to about 75 degrees.....no change in velocity.
     
  7. Marine sniper

    Marine sniper Well-Known Member

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    I will load some in my Wby brass also, makes for a beter test. I went shooting yesterday and somehow got a peice of Rem brass mixed into my Wby brass, +60-70 fps.....did not show any pressure signs though.
     
  8. kraky2

    kraky2 Well-Known Member

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    Sounds right (the diff between rem and wby). It's amazing the difference between the idea of having freebore and not. With my factory rifle with freebore the magic loads were 86.5 with the 180 tsx and 88.3 with the 200 ab. It's hard to believe that no freebore may equal 6-7 grains less but it sure can.