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Thread: 7.62x39 Bullet weight

  1. #1
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    7.62x39 Bullet weight

    Hi guys,

    Looking to reload for my Howa Mini 7.62x39. According to their website the twist rate is 1: 9.45.
    What would be the range of bullet weight it can handle?

    Looking at the cast lead projectiles by Robert from Putaruru/Tokoroa.

    308 151gr HP https://www.trademe.co.nz/sports/hun...7d2e7d3566-001

    303 204gr HP https://www.trademe.co.nz/sports/hun...7d2e7d3566-001

    Will try both subsonic and supersonic.

    Intention is to use for goats, deer and pigs in the bush.

    Thanks

  2. #2
    Just like Mimms the First
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    Slug your bore to get the actual dia .303 even in soft lead might not obdurate well enough in a .311 bore, certainly subsonic.

    And stick your cleaning rod down it to get your actual twist. 1:9.45 is pretty quick so should stabilise the heavies with full/compressed loads. You'd be able to get a bit of pace behind the 151s

    204gn will go sub easily (provided the diameter thing works out)

    Why the preference for lead rather than jacketed projectiles?

  3. #3
    Member Max Headroom's Avatar
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    Name:  Capture.JPG
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Size:  36.3 KB

    This is the sole listing for gunworks projectile supply in 7.62x39.

    No doubt there are more possibilities, but I suspect this bullet weight is the best option.
    RIP Barry S. 18/01/20

  4. #4
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    For full power loads, 123gr is your go to. There is 150gr stuff out there but the velocity kinda sucks. It's by no means the optimal weight for the twist but anything matched to a 1:9.45 with <30gr of powder will be walking down range.

  5. #5
    Member Micky Duck's Avatar
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    the top ones go great at subsonic and even better and just about subsonic.....

  6. #6
    Member Marty Henry's Avatar
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    303 is actually .311 due to the way the bore was measured so they should work fine. The British Lee Enfield twist rate was 1:10 so they will stableise.

  7. #7
    Member Cordite's Avatar
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    The 7.62x39 lends itself to subsonic loads, it's actually like it's coming into its own due to its the traditional fast twist of barrels chambered for it, which is a quirk of history.

    It's the same twist rate basically as in the Mosin Nagant 7.62x54R Russian rifle (later carried over by re-use of tooling to the 7.62x25 submachine guns and then to the 7.62x39 Soviet) and only slightly tighter than the 1:10 .303 rifles' twist. Both were designed for heavy 210/215grain bullets respectively.

    The Mosin was designed to shoot 210grain jacketed bullets at 2200fps and the Lee Enfield for 215 grain jacketed bullets at 2060fps (or 1850fps with the initial stop-gap 71grain black powder load).

    Note that cast, round nosed boolits are shorter than jacketed spitzers of same weight, so can be stabilised at a slower velocity by a given rifling twist than the (longer) spitzers.
    timattalon likes this.

  8. #8
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    Quote Originally Posted by Marty Henry View Post
    303 is actually .311 due to the way the bore was measured so they should work fine. The British Lee Enfield twist rate was 1:10 so they will stableise.
    Indeed. .303, are 311 or 310 bore diameter and 308 are actually slightly smaller diameter. However, the mini 30 had a 308 diameter bore but was still able to use normal 7.62x39 ammo. (Something to do with the way the throat was set up from memory, but please correct me if this is not the case)

    I have not slugged a Howa bore to see if it is .311 or .308 as being an American brand there is a chance it could be either. (Last I heard they were actually made in Japan)

    Longer heavier bullets such as the 180s etc may need to be checked to see if they fit in the magazine....especially if using longer "pointy" bullets. If going subsonic then velocity will be fixted at around 1000-1100 fps (otherwise it is not a subby anymore and just slow) so to increase the energy the bullet weight will need to come up....

  9. #9
    Just like Mimms the First
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    Thanks for correcting me all. I didn't follow any of the links so didn't have actual dimensions and took it as a literal .303"

    For reference 7.7 millimetres = .303 which is bore/land diameter.
    7.9mm = .311 (nominal groove - what you need gas seal against)
    and 7.62 is .300" (bore/lands)
    timattalon likes this.

  10. #10
    Member Cordite's Avatar
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    Quote Originally Posted by mimms2 View Post
    Thanks for correcting me all. I didn't follow any of the links so didn't have actual dimensions and took it as a literal .303"

    For reference 7.7 millimetres = .303 which is bore/land diameter.
    7.9mm = .311 (nominal groove - what you need gas seal against)
    and 7.62 is .300" (bore/lands)
    It's something to do with American style of measurement vs the European style of measurement.

    Americans measure bore groove to groove (.cf .308 is a .308" bullet going into a land to land bore of .300" but a groove to groove bore more like .308").

    Europeans measure bore from land to land (cf. .303, which is a .312 bullet going into a bore of .303 land-to-land but with a groove-to-groove bore more like .312 or deeper).

    So a .311" bullet will fit down a .303 barrel quite nicely, though it might not quite fill the grooves as intended. A .308" bullet will likewise also squeeze nicely against the lands in a .303 barrel, but again will not obturate to fill the grooves that well, risking suboptimal accuracy, especially in typical shot out .303 barrels.

    I don't know about using .303 (.311") or 7.62 Russian (.311") bullets in a .308 barrel, I have no reason to try it.

  11. #11
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    A friend bought the 151/2 308gnhp cast proj for his x39 mini & we experimented last weekend to get subsonic rounds. We pulled a box of Tulammo fmjs & emptied the cases of powder (25gns+/-3gns) measuring the powder weights to get an average. We started measuring out the powder beginning @ 12gns = 1300fps ave, dropped back to 7.5 = 750fps ave, & settled on 9 gns for 1010fps. We didn't do the accuracy test as he'll be using them in the bush on goats & deer out to 100 yds so reckons @ that range he'd better hit them or he'll go home. The animals will be very unwell after encountering those bullets... he's a very good shot.

  12. #12
    Member Dead is better's Avatar
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    We were lobbing hornadys onto a sandhill at 500m and got some pretty good feedback. There was approx 1.7m drop which i noted for later to try to help my mate sort out his drop chart. I gotta say i was impressed with the transonic performance of these rounds. Hitting the same point more or less

  13. #13
    Member Marty Henry's Avatar
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    Putting this round through a rifle of greater barrel length and accuracy potential than the aks, skks and sks of the past will suprise many people. It's easy to see why it parented so many of the smaller precision cartridges.
    timattalon likes this.

 

 

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