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Thread: .308 in 7.62x51

  1. #1

    .308 in 7.62x51

    Thoughts on .308 hunting ammo through 7.62x51?

  2. #2
    That depends on the rifle. Dimensions are not a problem, because Winchester pushed the US Arm into adopting the 7.62x51mm by commercializing as the .308 Winchester.

    But many older 7.62x51mm rifles were conversions, made for lower pressure loads than commercial .308. Examples are the Spanish FR-7, FR-8, CETME, Enfield conversions, the Ishapore Enfield.

    Also, the gas operated semi-automatics are designed for a gas pressure curve which does not input too much gas to the piston, so some powders, even at less than maximum pressure, will beat up the action. Examples are the M1 Garand, M-14, original AR-10.

  3. #3
    thinking mauser 98 PH from santa barbara with target 7.62 barrel

  4. #4
    The quality of Santa Barbara Mausers varies, some of it due to manufacturing, some in metallurgy, a lot in the prior use. There are rifles built at home off the stripped military actions which came on the market in 1968, and rifles built by firearms manufacturers and skilled gunsmiths.

    Since you are in the UK, may very well be a Parker Hale, who built a lot of rifles on the Santa Barbara Mausers in the 1970s, including some .300 Win Mag. They built target rifles, and they had their commercial .308 Winchester sporting rifles rebarreled and restocked for target use. Parker Hale would have proofed all these rifles. Take it out of the stock and look for proof marks.

    You need to check it out with a set of headspace gauges, of course.

  5. #5
    Mine is stamped "20 tons" however that compares

  6. #6
    Quote Originally Posted by bewsher500 View Post
    Mine is stamped "20 tons" however that compares
    nah, that's just the weight of your new target barrel ;-)

  7. #7
    First thought, best not to risk it. Can't remember the information source but recollect 7.62 ammo ok in .308 but not in reverse. Down to pressure differentials?

  8. #8
    I was under the impression that USA made factory ammo is likely to be OK because over there they are more cautious.
    Euro ammo though has a bit more "oomph".
    As said though,check headspacing.

  9. #9
    Both cartridges have a maximum pressure of 60,191 PSI. Since all were adopted for use with NATO spec ammunition, there should be no issue with SAAMI spec 308 ammunition.


  10. #10
    The proof maximum for the .308 Win, the 7.62x51 NATO and the .30-06 are all the same: 67,500 PSI........ depends... US Army, NATO, SAAMI, and CIP vary.

    Current ammunition specifications ( not maximum) measured by piezo gauge, are
    7.62x51mm US Army chamber pressures = 50,000 PSI originally. Later, this was changed to 50,000 CUP MAX, another source of confusion.
    7.62x51mm NATO max chamber pressure = 60,200 PSI
    7.62x51mm NATO proof pressures, min to max = 62,000 PSI to 67,500 PSI

    .308 Winchester SAAMI chamber pressure = 62,000 PSI
    .308 Winchester proof pressures, min to max = 83,000 PSI to 89,000 PSI

    Because many early 7.62x51mm rifles were conversions of older rifles, the early NATO spec for ammunition was 45,000 PSI, same as the 7x57mm Mauser for which they were originally designed. The FR-7 is one example. Another example is the British Enfield, rated to 49,200 PSI. The Spanish FR-8, based on the M-43 Mauser, could handle higher pressures, but they had to have one set for the FR-7, FR-8, and CETME - the lowest common denominator.

    Later, as all new rifles came into service, and the pressure measuring was standardized from a CUP, to a mix of CUP and piezo, to all piezo, and pressures raised, the older rifles used special ammunition with the same muzzle velocities, but lighter bullets. Spain had some 112-gr ammo, some 123-gr, etc.

    But back to these old M98 target rifles.... we can assume they were loaded to fairly high pressures. If someone abused any rifle by loading it to near proof pressures repeatedly, they are risking metal fatigue. So check the headspace first, with a .308 Winchester gauge (not military ), to avoid a case separation with a high pressure load.

    When I get a chance, I will go shoot some of my old 7.62x51mm ammunition from the US, England, Spain, Greece, etc, going back to the 1950s and all recent stuff, through the same rifle, and through a chronograph to see what it is putting out and deduce some pressures from that. I am curious myself as to the actual vs the specs for each.

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