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Overpressure

Discussion in 'Handloading and Reloading' started by kestak, Dec 14, 2012.

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  1. kestak

    kestak Member

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    Greetings,

    caliber 30-06
    Powder big game 56.6 grains (way under maximum load that is 59.2 or 60.7)
    Primers Winchester rifle magnum
    Brass FC
    Bullets Sierra Pro-hunter 150 grains and Hornady 150 FMJ and M1 Ball 147 grains

    I shoot those in my savage model 10 and everything is ok. Sometimes I got a bolt a little bit hard to close because I size on the tight side.

    I shoot those in my Howa 1500 and the rounds loaded with Sierra Pro-Hunter show MAJOR signs of over pressure: cratered primers, hard to open bolt. BUT THE OTHER rounds with the other bullets do not show any sign of pressure in that rifle.

    Anyone got an explanation? I have a couple of ideas, but I want to hear from you before guys. It is the first time I get something like that in all those years of handloading.

    Thank you
     
  2. rcmodel

    rcmodel Member in memoriam

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    Well, maybe the Pro-Hunter is a flat base bullet, and the other two are boat-tails.

    As such, the Pro-Hunter has a lot more bearing surface, which results in more bore friction and higher pressure.

    rc
     
  3. 45lcshooter

    45lcshooter Member

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    All your cases trimmed to same length? All your COAL length the same?

    I dont know if you sorrted cases before loading between different bullets.
     
  4. tightgroup tiger

    tightgroup tiger Member

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    That's probably it,
    or maybe the Sierra bullets are hitting your riflings because the chamber in the Howa is a tad shorter than the other rifles.

    Try seating them a little deeper and see if it helps anything.
     
  5. kestak

    kestak Member

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    Same brass, trimmer brass, chamfer, deburred, annealed.

    Yep You got the two things I thought about:
    1 - Flat base bullet instead of boat tail.
    2 - Shorter chamber and the bullet "curve is fatter" than the two other bullets.

    Now my question: Can I sit the bullet a tad deeper and keep same powder or I am better to back down the powder 1 grain too? Maybe 2 grains?
     
  6. rcmodel

    rcmodel Member in memoriam

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    If you are already getting pressure signs in the Howa?

    No you can't seat deeper and keep the same powder charge.

    You need to work up a load for it from the get-go all over again.

    But it might save a lot of grief to settle on one kind of bullet or the other first.

    rc
     
  7. kestak

    kestak Member

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    Ok. thank you. Got it. I knew the answer but hope it would be different. You know, it is the Holidays time...oh oh oh! ;-)
     
  8. gamestalker

    gamestalker member

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    This is the reason why we are supposed to re-work loads every time a component change is made, or, if changing actions. This does not mean a reloader can't develope a load that will function in various other actions, it just requires finding the load and specs that will function reasonably well in all of them, much like factory ammunition is intended to do.

    GS
     
  9. Pacsd

    Pacsd Member

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    What manual are you using? In my Sierra Suite I don't see any loads that call for mag primers. And, I'm not sure what you mean by "Size on the tight side". Now, as far as pressure signs, I'm guessing your COAL is into the lands. Now add mag primers. That could have an affect. Have you ever truly established your optimum COAL according to your chamber for each bullet ogive? All my Howas seem to have a larger chamber allowing a longer COAL. I don't see any reason why you can not seat your bullet deeper to get it off the lands and keep the same powder charge.
     
  10. john wall

    john wall Member

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    Turn in your bullet seating stem 1/4 turn and see what you get.
     
  11. rcmodel

    rcmodel Member in memoriam

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    So, you are suggesting that after he said he is already getting "cratered primers, hard to open bolt", he just seat deeper and see what else happens next?

    Mercy! Mercy!!

    rc
     
  12. ArchAngelCD

    ArchAngelCD Member

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    First, you are using a magnum primer when the Ramshot data calls for a WLR primer.

    Second, you didn't tell us the COAL of your loaded round.

    I have the same rifle you have, a Howa 1500 in 30-06 and that rifle seems to handle higher pressure loads better than a few other rifles I own. (except for the Mauser action based rifles)

    I'm asking about the COAL because you said that ammo shoots fine in the Savage and the problem shows up in the Howa. Is it possible the bullet is jamming up against the rifling since you are also reporting a hard to close bolt? (or was the hard to close bolt in the Savage only?)
     
  13. VAPOPO

    VAPOPO Member

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    I'm asking about the COAL because you said that ammo shoots fine in the Savage and the problem shows up in the Howa. Is it possible the bullet is jamming up against the rifling since you are also reporting a hard to close bolt? (or was the hard to close bolt in the Savage only?)


    My guess too. Back off 10% on the load, change to a WLR primer and find out if your OAL is to long.
     
  14. kestak

    kestak Member

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    Greetings,

    1 - No, I will not just push the bullet back and shoot. I am reworking all the load.

    2 - Yes I use magnum primers because when I worked the load with the Savage 110 (not 10 as I wrote, it was a typo), it was giving me the best group. It was also giving the best group in my best friend CZ too. Moreover, with magnum primers, I had the smallest deviance in velocity.

    3 - I just took some measurements with my 30-06 RCBS Measurement tool for the rifling of that Howa and the rounds I have:
    Tool with the nylon cap: 0 - 10
    M1 Ball ammo : 0.5 - 39
    Pro-Hunter : 0.5 22

    a) it seems both my rounds are going into the rifling. I plan to test today pushing back some rounds and trying to close the bolt to see if the hard to close was the case or the bullet being pushed back.
    b) it seems the pro-hunter is less in the rifling than the M1 ball, hence a more aggressive ogive curve. It puzzles me a little because I would bet the jacket is thinner than the M1 ball bullets. So it "may" be the flat bottom creating the overpressure signs.

    Archangel, what bullets are you using and what COAL with your HOWA? With the M1 ball, I am at the closest to the tip of the bullet crimp grove.

    DISCLAIMER: Because the M1 ball does not create overpressure signs DOES NOT MEAN there is no overpressure. I just want to put that out front for those who may know less than us more experienced handloaders.

    Thank you
     
  15. Walkalong

    Walkalong Moderator

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    When it comes to case capacity, what is important is how deep in the case the base of the bullet is. Then figure in the type of base as well. You can only directly compare like bases. The boat tail has a little space around it, adding to case capacity.

    If you are loading M1 ball into the lands, and have a reasonable amount of the bullet in the case neck, the Howa must have a very short throat. That's generally good for accuracy, but it affects pressures as well. The Weatherby rifles had long throats to help keep pressures down with those massive powder charges.

    There is more than one sweet spot for any powder bullet combination. You just need to find one that does not exhibit pressure signs.
     
  16. ArchAngelCD

    ArchAngelCD Member

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    I'm using several loads right now.
    For practice I'm using a 168gr Hornady or Sierra match bullet.
    Hornady 168gr match bullet
    Win/Rem brass
    CCI LR primer
    58.0gr H4350
    OAL - 3.235"

    Sierra 168gr match bullet
    Win/Rem brass
    WLR primer
    58.0gr H4350
    OAL - 3.235"

    This is the hunting load you're probably most interested in seeing.
    Sierra 165gr GameKing bullet
    Win/Rem brass
    WLR primer
    58.0gr H4350
    OAL - 3.225" (0.01" shorter OAL)

    If I use IMR 4350 the charge weight goes down slightly to 57.0gr under the same bullets.
     
  17. kestak

    kestak Member

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    How come you guys, old timers, are always using a powder I do not use or have? ;-)
    I am streamlining my powders since a few years and decided to settle on TAC, WC844, Big Game, I4895 and 4830sc (is it 4830 the numbers? but it is the short cut for 270) for my rifles....:)

    Today's measurement:

    M1 Ball OAL - 3.325
    Pro Hunter 2130 Before readjusting - 3.225
    Pro Hunter 2130 AFTER readjusting with my new measure - 3.025 !!!!!!!!!!!!!!!

    This is waaaaaayyyy to low. I used some ash from my fireplace and blackened a bullet with the 3.225 measure. I closed my action on it and re-opened it and no mark on the bullet. Also, I took 5 cartridges, measured them before and after cycling 3 times!!! in the action and there is no change on the OAL. I guess I need to use that tool better.

    This morning I am going to try 7 different loads in that order to see if I see any pressure issue:

    All big game powder:
    LRM primer
    54.5gr
    55.0gr
    55.5gr

    LR primer
    54.5gr
    55.0gr
    55.5gr
    56.6gr

    Same OAL than before (3.225") for all rounds.

    Thank you
     
  18. Jaxondog

    Jaxondog Member

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    I thought everybody has used IMR 4350. especially more experienced handloader's.
     
  19. Sport45

    Sport45 Member

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    Not to pick nits, but isn't M1 about 173gr? If your bullets are military 147gr FMJ I think they may be M80.
     
  20. kestak

    kestak Member

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    You are right. I meant M80.

    Did my tests yesterday at my friend house. I was the youngest guy there. Without me, average age was 70 years old...hehe.

    All the charges showed what I thought pressure signs. Those old geezers told me per the primer look they all seemed fine and some guns did not have the nice little dimple we have to expect. I'll try to get a picture soon of the rounds I fired yesterday ASAP.
     
  21. Jim Watson

    Jim Watson Member

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    Back in the days before bullet companies had pressure guns, Speer said that when ONE excess pressure sign is apparent, you should reduce the load by 6%.

    And that back when OALs at factory or magazine length were acceptable and we were not chasing the lands in an effort to make a hunting rifle shoot like a benchrest gun.
     
  22. kestak

    kestak Member

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    [​IMG]

    [​IMG]

    Funny thing, look at the 54.5 and 55.0 primers dimples compared tothe other ones. They look more craterred. And BTW, I manually measured with two scales each charge.

    Right ammo, the FMJ, is with wolf mag primers. Other is winchester mag.
     
  23. rcmodel

    rcmodel Member in memoriam

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    I'm not seeing a problem.

    None of the primers look flattened clear to the edge of the primer pockets.

    That right there is a pressure sign.

    Firing pin dents, dimples, and dings are not.

    rc
     
  24. kestak

    kestak Member

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    Than you. That means I saw a problem when there is not one...and I did not even begun to dip in the eggnog and punch yet! ;-)
     
  25. Walkalong

    Walkalong Moderator

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    Right, the edges are still nicely rounded. No worries from the looks of the primers.
     
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