Gewehr 88 Low Pressure -- What Should I Bump It To?

Discussion in 'Curio & Relics Forum' started by Josh Smith, Nov 13, 2011.

  1. Josh Smith

    Josh Smith New Member

    Joined:
    Nov 10, 2009
    Messages:
    69
    Location:
    Wabash IN
    Hello,

    My load for the Gewehr 88 with a bore that slugs 0.318" is as follows:

    Winchester case formed from .30-06 Winchester case

    0.318" 150 grain spitzer bullet

    46.5 grains Varget

    Federal large rifle primer

    Now, I'm having signs of gas leakage around the neck. I'd like to bump it up a little bit to make that stop, but it's probably due to the "S" rethroating.

    I don't remember the upper limit for the 7,92x57J cartridge, or for the rifle. I was thinking 40,000PSI, but am not sure. Could be 45,000 PSI. One is CUP.

    I do believe I'll stick with 40,000 PSI though.

    I was going to start bumping it a grain at a time, but I'm really not sure when to stop. I know that by the time it shows pressure signs I'll be exceeding the action design.

    I'd love me a pressure gun, but since I don't have one, I'll have to take educated approximations from you all.

    So, where do you suppose I should stop? What load would max at 40,000 PSI?

    Thanks,

    Josh
  2. 300 H&H

    300 H&H Active Member

    Joined:
    Apr 1, 2007
    Messages:
    1,850
    Location:
    Iowa
    Josh,

    Back in the day the wildcatters used to work up to maximum loads by measuring the case head for growth. If it is only 1/2 thousands bigger, some thing moved too much and the preasures are too high....This was of course using an action of more strength than yours. But I believe it still has merrit in your rifle. Watching for primer back out, and how hard the bolt lifts "can" be signs as well. Before trying how ever I would look high and low for an artical in a publication such as gun digest or shooters bible, as years ago some one may have written about the Gew 88, as many were around surplus here. Does yours have the barrel jacket? Military models usually do, but commercial sporters do not. There is an absoulute mountain of information that is not on the internet, and I am betting what you want isn't here. But I also believe it is out there on real paper, somewhere!

    Regards, Kirk
  3. Jim K

    Jim K New Member

    Joined:
    Dec 6, 2009
    Messages:
    6,400
    The original factory sporting loads for that caliber and that bullet approximate weight ran 40k psi, so I think I would stick to that pressure range. The rifles are stronger than some writers say, and routinely fired the 7.9 (8x57JS) military load after the chamber neck was reamed to allow the case neck room to expand, but there is no point in going beyond the original pressures for sporting purposes.

    Jim
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