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Thread: Blown case bottoms.

  1. #1

    Blown case bottoms.

    Just been firing my first lot of handloaded .243 ammo. Part of round development process to get optimum seating depth. Had 3 batches (4 rounds in each batch) of ammo: One batch just touching lands, one seated into the lands and one batch off the lands. I forget the exact measurements. (Don't worry, I got them written down!).
    All cases were Hornady once fired (saved up from factory ammo).
    Bullets were 80gn Noslers.
    Powder was 37.5 gns of vitavari N140
    Rifle is P-H Safari Deluxe.

    When fired, almost all of the cases blew out on the base at the point where there's a slot in the bolt head where the retaining catch runs through. At this small point the case base is unsupported. In some cases there was just a small raised rectangle of brass at that point, but in others it had blown out enough to crack and allow combustion gases through, which have caused burns on the outside of the case (around the primer hole) and some minor pitting on the bolt face.

    The rounds that were seated off the lands were perhaps the worst, with all of them affected to some degree, and 3 out of the 4 having blown right through, but not sure if this is significant. (This was also the batch with the best grouping!).

    What's going on here?

  2. #2
    i'm not following your description, but you definitely have issues. could you take some photos? oh, and don't shoot anymore for the time being.....
    callum ferguson builds my rifles, because he is the best and i'm worth it....

  3. #3
    Hard to say what else may be wrong but you have exceeded Vitavouri's recommended charge of N140. There is a reason they publish reloading data...


  4. #4
    Massively over pressure. The PH's are renowned for their slack chambers and this combined with TOO MUCH POWDER means you are risking a blown action and serious personal injury! I would expect opening the bolt would have been hard work too and this is another sign of over pressure.

    Please pull this ammo and start again.

    Reloading may be easy but getting your face rebuilt after a breech failure is not.
    Knowledge is knowing that a tomato is a fruit. Wisdom is not using it in a fruit salad.

    Amateurs practice until they get it right. Professionals practice until they never get it wrong.

  5. #5
    you are getting over pressure sign on the case head im guesssing and the square marks you are seeing the extrater port

    is there a small round dimple there as well?
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  6. #6
    Ok, I get the idea - TOO MUCH POWDER! I though they made big bangs!
    Thanks for the data Marcbo.
    I made these rounds with help from my local RFD who also runs a reloading club. He looked up the powder requirement in published info he had, but in future I think I should do my own research!!!
    Will try and take some photos tomorrow to show exactly what happened.
    Don't worry, I won't fire any more - they're all gone!

  7. #7
    As Marcbo says you have exceeded the maximum recommended load, and these were your first reloads?
    You should develop a load suitable for your rifle starting with the recommended start load and work up, not start at maximum or in your case in excess of maximum. Perhaps you should go back and re-read the warning notice about load data in the front of your reloading manual. I take it that you do have a manual and haven't relied solely on what your local RFD has told you????
    It's the calibre of the shooter that counts not the calibre of the rifle.

  8. #8
    The issue is VSS that increases in pressure are exponential especially at higher charges. Also seating in to the lands will cause a similar rise in pressure, combine these and you end up in your situation.

    Take care and best of luck
    Knowledge is knowing that a tomato is a fruit. Wisdom is not using it in a fruit salad.

    Amateurs practice until they get it right. Professionals practice until they never get it wrong.

  9. #9
    The PH's are renowned for their slack chambers
    What utter tripe !

    In all the P-H rifles that I own and dealt with I have NEVER found this.

    The OP has obviously over loaded the cartridges and this is down to his doing and got nowt to do with the rifles design or manufacture what so ever. In fact some lesser makes and designs might well have blow bits like extractor out.

  10. #10
    Massive overpressure. Be thankful it's a strong action.
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