Reload .338-.378KT for Nosler 250gr w/Retumbo

Discussion in 'Reloading' started by terjeness, Aug 23, 2011.

  1. terjeness

    terjeness Well-Known Member

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    I hope there are some seasoned wise guys (in the best sense of the word) out there who can give me some reloading data for my 338-.378KT. I want to try Retumbo and 250gr. Nosler Spitzer bullets. I'm also considering the Barnes TSX 250gr. Anyone with experience to share?
     
  2. backwoods83

    backwoods83 Well-Known Member

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    338x378wby improved or kt use a couple grains less that max for a 338x378wby mag and H1000 may work better, I don't know a whole lot about em, just what I've been told. I know basically that kt is just the initials of the designers but what I mentioned should be a good starting point.
     

  3. terjeness

    terjeness Well-Known Member

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    Thanks, Backwoods, for your reply!
     
  4. sambo3006

    sambo3006 Well-Known Member

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    The 338-378 KT (Keith-Thompson) is a 338/378 Weatherby case shortened by 1/4", so it will have a fair amount less powder capacity than the parent cartridge. There was an article on the 338/378 KT written by Ross Seyfried in Shooting Times back in 1985 or 1986. I have the magazine and if I can find it I'll post the data. I don't think it would be a good idea to use 338/378 Weatherby data and back off a couple of grains. That might still be too much powder. More realistic might be 338 Remington Ultramag data but I don't know that for sure.
     
  5. backwoods83

    backwoods83 Well-Known Member

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    What I found on it was that it is shorter but most of that is in the neck length, it still holds 121grns H2O not a noticable difference from the weatherby. The only data listed was 96grns H4831sc under a 250grn partition at 3010fps in a 26" barrel. So with that said I'm thinking retumbe may end up being compressed and still be to slow under a 250, might work well under a 300grn.
     
  6. terjeness

    terjeness Well-Known Member

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    Thanks to both Sambo and Backwoods!
    As I'm looking at Hodgedon's data, it startes (for the .338-.378Weatherby) with 108gr and goes up to 115gr. However, I am considering starting with 105gr and work my way up from there.....
     
  7. RDM416

    RDM416 Well-Known Member

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    I shoot a 338 Khan which is a 338/378 improved. However it has just a bit more case capacity than the factory 338/378 so I would think my loads would need to be backed 4 or 5 grains to start.

    250 SMK / RL 25 - 107 grains / Fed 215M 3240 fps

    300 Berger / Retumbo 104 grains / Fed 215M 3018 fps

    250 SMK / Retumbo 111 grains / FED 215M 3230 fps

    I am a fan of SMKs and Bergers, don't have any data on the bullets you mentioned. One new bullet I just started messing with is the Cutting Edge 225 grain.

    This may not be my final load as I still want to play with some other powders.

    225 CE / RL 25 108 grains / Fed 215M 3400 fps

    Good luck, and be careful...... start low, if you try any of these loads.
     
  8. terjeness

    terjeness Well-Known Member

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    Thank you, RDM, this is very helpful. I will start out with less powder and look for signs of stress and Crono at the same time.
    terjeness
     
  9. sambo3006

    sambo3006 Well-Known Member

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    I would NOT do that!!!!!!!!

    The 338-378 KT mirrors the performance of the 338 RUM and that would be an over max charge of any powder in the RUM. The KT was based on the 378Wby (back before there was a 338-378 Wby) and the whole case, shoulder and all was shortened 1/4". If you line up a 338-378 KT case next to a 338-378 Wby case, you would see this.

    I'll dig around this evening to find the magazine with the load data.
     
  10. RDM416

    RDM416 Well-Known Member

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    Terjeness,

    It sounds like you better listen to Sambo, I am not familiar with the 338KT and wrongly assumed it was pretty close to the 338/378, apparently it is not. The 338Khan is close enough in case capacity that loads for it and the 338/378 are pretty much interchangeable. The loads I listed are top end pressure wise for my 338Khan so even backing off 4 or 5 grains may not be enough. Maybe Sambo can find that magazine article or someone more familiar with the KT can make some load suggestions, but don't try my 338Khan loads. Sorry, my bad.
     
  11. terjeness

    terjeness Well-Known Member

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    Thanks, guys. I appreciate your advice. I have shot this one in the past with 101gr. 4831 w/250gr. Sierra Spitzer Boat Tail. But do not have the velocity any longer.
    F. R. Mitchell in a Champlin ARms Keith Grade rifle with a 25" barrel shot a 250gr. Nosler with 98.gr. RL22 at 3000f.sec.
    However I do not have any data with Retumbo yet.
    I have loaded up some loads starting at 99gr. in 1gr. increments. Will try tomorrow and look for stress signs as I go. However, despite Retumbo being temp stable, I am a little concerned with the hot temps now. It will probably be 20Celcius or more tomorrow morning.
    If you find any more info tonight, I'll be very curious,
    Terjeness