Viewing 2 reply threads
  • Author
    Posts
    • #27874
      Harter
      Participant
      • Gold
      • ★★★
      • Posts: 76
      • Comments: 807
      • Overall: 883

      I’ve been using slow powders to get the mostly full case and better velocities from cast for some time with the idea that if it’s slow enough in a small case you can’t get enough in there to do any damage . A 200gr cast in a x39 for example with IMR 4350. It barely clears the 30 kpsi clean up point .
      Cartridge in question 257 Roberts.
      The sister cartridges 6mm Remington, 6.5 x 55 and 7×57 show data for H1000 with 100,140 and 168 gr bullets (jacketed) at more or less case capacity but only IMR and H 4350 and 4831 show up for the 257. I have some W857 that I would like to try which is suggested to be compatible with H1000 data so it seems reasonable that I should be able to use it safely.

      How much can load of the slow powders be reduced ? 4350 or 4831 for example.
      If I have for example a rifle that is just under maximum headspace, was chambered with a brand new reamer , I use light brass and my bullet of choice seats 1/10 long . Isn’t that like starting a last cut match chamber with zero headspace and a breach seat leade up to 2 gr light . When I look at the max load in the 2nd rifle it might not even chamber while the 1st may not be even close to maximum.
      I know …. I have 5 books, Aliant, Hogdon, IMR book marked and 2 apps . But the Lyman CBH doesn’t use slow full case powders and has an aversion to 2000 fps in the 257 . I have an aversion to shotgun sized charges of Unique in rifle cases . I know that my 257 chamber is fat and that Norma brass is nominal and that this rifle will load well out past the book length and at a start load for jacketed with jacketed it is very happy . I didn’t Chrony the load but it shoots little groups and killed a pig with a less than optimal shot choice so I’m happy there. I’ve had no known problems with the 06′ at 36 gr of 4350 with start loads of 40-52 gr and in a 32 Rem 3 gr under start loads for 32 Winchester Special .

      I’m thinking as I write wouldn’t reducing the load be a lot like fire forming an improved case with a start load ? I can’t think of a major case change from standard to AI, 280 Rem maybe .
      I know there are physics and curves involved and that case and cal play a roll. I just don’t want to stray to far out in the weeds with this rifle in the effort to get a 38-40 kpsi load in the middle 2000 fps with a 260-120 FP NOE .

    • #27875
      Goodsteel
      Keymaster
      • Gold
      • ★★★
      • Posts: 208
      • Comments: 2452
      • Overall: 2660

      If that’s the rifle I blued for your father, you better take it easy on the load data. I told him that Spanish SR was a soft one and to keep the charges light.
      If that’s the same rifle, it will not tolerate excessive pressure of any kind. The bob is a very tapered cartridge that is not easy on the bolt face/recoil lugs.
      Reducing slow powders is a recipe for SEE in that cartridge in my opinion, but Larry could speak better to that than I can.

    • #27877
      Harter
      Participant
      • Gold
      • ★★★
      • Posts: 76
      • Comments: 807
      • Overall: 883

      That is the situation.
      The finish reamer left it with rather full shoulders and the ability to leave the load long or allow the jump with jacketed. Both proven but not always reliable means of reducing pressure. I’m kind of left with normal proven loads without pressure data that could be doubled or to seek a low pressure near impossible to overload powder. The last option is of course ,painting the extremes, a 40 gr angry 25 ACP type load.
      I fully understand that this platform is a plinker platform that can be medium game capable but also that this isn’t a place where I can simply substitute 250 Savage data and run with it .

Viewing 2 reply threads
  • You must be logged in to reply to this topic.

© 2017 Goodsteel Forum. Designed by Covalent Designs, LLC.