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Thread: How tight is too tight - bolt

  1. #1

    How tight is too tight - bolt

    First dabble at reloading over the weekend - shot a five shot 1/2" group with 90gn Nosler BT's over 42gn of 414 (which is right in the middle of the range for this powder bullet combo) so was obviously quite chuffed

    However, couple of things I wasn't sure of:
    1) the bolt handle was slightly tight on a couple of rounds - nothing major, but maybe 20% stiffer to initially open the bolt than normal, but the case withdrew and extracted with no additional force. Is this a sign the pressures are too high? No sign of any problems on the primer though.
    2) There was a lot of condensation in the chamber after one round - barrel was warm, sunny dry day but when I chambered and ejected the next round I discovered it had quite a lot of moisture on the surface. Never had this before from factory loads. Any thoughts?

    Probably worrying over nothing, but better safe than sorry!

  2. #2
    Looking at primers and trying to guess pressure levels is quite futile. The differences in primer cup metals can make it very misleading. I have an article where they at the Pedersens Ranch lab they got pressures in excess of 100,000 PSI before a primer pocket expanded and the primer looked the same as that on a 50,000 PSI load with just visual examination.

    If to bolt lift is stiffer then you have more pressure and if I were you I would be backing off slightly. I have never noticed condensation on ejected cartridges so sorry I cannot comment.

  3. #3
    Possibly a little oil from somewheres in the action?, condensation as in H2O I would struggle with, the forces involved when firing a round are immense & enough to bring an oil into aerosol, out of any little spaces, oil on cartridges WILL also INCREASE your pressures quite a bit, as will rain in the magazine spaces.
    (The Unspeakable In Pursuit Of The Uneatable.) " If I can help, I will help!." Former S.A.C.S. member!

  4. #4
    I have never seen condensation but I shoot in drier climates... Odd though. Agreed as to the primer visualization. It is relatively worthless as an indicator. Any condensation or lubricant in the chamber can elevate chamber pressures so be careful.~Muir

  5. #5
    Guess it could have been oil from somewhere as I'd just cleaned the rifle, but it certainly felt like water to the touch, and dried quickly once I left the bolt open and let a bit of air through the warm chamber. All a bit odd, but now wondering whether stiff bolt is more linked to moisture in the chamber than "hot" loads. Will back of a touch and then work back up again slowly - shame as the old girl certainly like that recipe - best group I've ever shot - three through the same hole and one each side

  6. #6
    If you have shot in the rain or even on a cold day then put your rifle in a warm vehicle / house, this will cause condensation, I have this problem most nights after lamping, maybe this could be the source of your water?
    (The Unspeakable In Pursuit Of The Uneatable.) " If I can help, I will help!." Former S.A.C.S. member!

  7. #7
    Account Suspended
    Join Date
    Jan 2010
    North Yorkshire
    Check your head space on your cartridges also check case length if to long and above manufactures tolerences the brass could lead into the throat a little which is the major cause of excessive pressure build up along with the bullet being seated to far out of the case.
    Smoke in a dummy round or use engineers blue on the bullet head seat it oin the rifle and see if any marks are removed fron the bullet head keep seating it until there is no evidence of marking at canulure point on the bullet then send your adjusting seating die down another couple of thou on top of that, it should sort out over pressures and extraction problems , The observations above I presume of course the correct powder and primer combination loadings have been observed.
    Cant help as to why condensation present.
    Last edited by Mannlicher_Stu; 13-04-2010 at 14:39.

  8. #8
    Measured the chamber using a dummy round and the jump is 10 thou onto the lands. Cases were fire formed and trimmed so all should be good there. 'Twas a warm sunny day and rifle and bullets had all come from the house so shouldn't have been cold enough for condensation - now wondering whether it was in fact oil rather than water... No other logical explination!!

  9. #9
    SD Regular
    Join Date
    Dec 2008
    East Midlands M1/M69 Junction 21
    A reasonably accurate test for over pressure is this. Use a micrometer or similar to measure the case head expansion of two or three fired rounds of factory ammunition in your rifle.

    Then reload (as normal) these with your reload "recipe" fire them and measure the case head expansion.

    If the new measurement is greater on the reloads than on the factory you are certainly reloading to a higher pressure.

  10. #10
    75. Caprelous asks a good question and I have a couple more.
    What calibre are you reloading? 243 Win?
    You say 'Cases were fire formed and trimmed...'
    Between fire forming and trimming did you neck size or full length resize?
    Thanks JCS

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