Flatning Primers and Blowing Out Primers

Discussion in 'Reloading' started by Prairie Dog50, Dec 27, 2010.

  1. Prairie Dog50

    Prairie Dog50 Active Member

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    I have a savage model 12fv chambered in .22-250 with a heavy varmit barrel. We have tried a variety of different hand-load recipes with a variety of powder and a variety of bullets in type brand and weight. All of this of course is done with the proper safety procedures; always starting with the minimum charge listed in the speer reloading manual, and the annual Hodgon's magazine reloading manual and progressively working our way up until we see signs of excessive pressure.. We can get very tight groups with this gun and these hand-loads, however in most cases we can never get past the first minimum charge without flatening or blowing out primers. Oh by the way we use CCI 200 Large Rifle Primers. We were thinking of maybe starting with the minimum charge and working our way lower in half grain increments until the primers quit flatening and when were getting acceptable group sizes. Is there any danger in this?? Or is there perhaps a better way to solve this problem??
     
  2. parkj5

    parkj5 Well-Known Member

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    Man i got a ruger m77 thats doing the same dang thing.i have not blown any primers yet but they sure come out flat.bolt does not even get sticky.mine is a 25-06
     

  3. dmaxthad

    dmaxthad Member

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    Dec 28, 2010
    I have a Ruger M77 in 270win that flattens primers ever so often. Just the other day it did it with factory loaded ammo.
     
  4. J E Custom

    J E Custom Well-Known Member

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    If you are getting pressure at the starting loads there are several reasons.

    Look at the fired brass and insert a new bullet in the case, (It should fall in). If it doesent go in
    easy then you have a tight neck or it is longer than the neck portion of the chamber.

    If it is not to long (Can be fixed by trimming) then you may/must turn the necks down.

    The other thing it could be is bullet seating depth . If it is touching the lands at all it will raise
    the pressure and it will need to be seated .020 off the lands and then you can work closer to
    the lands in steps of .005.

    Some chambers have no free bore and this is a common condition if not dealt with.

    There is nothing wrong with the primers as long as it is the one listed in the load data.

    I hope this helped.

    J E CUSTOM
     
  5. noone

    noone Member

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    The length of the neck on your brass could also cause problems. If the neck is too long the chamber in your new rifle, when you chamber the round, the end of the neck gets crimped onto the bullet causing excessive, and erratic pressures.

    Earlier in this thread, bullet seating depth was covered really well so I won't go into that.

    Other causes could be oil or solvent in the chamber, improper headspace (even with a new rifle), short throat (covered with bullet seating depth).

    I suggest making sure there isn't any oil or solvent in the chamber, a seating depth gauge, trim the case necks, and have headspace checked.
     
  6. Trickymissfit

    Trickymissfit Well-Known Member

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    awhile back I ran into a similar problem with Blackhills brass. The necks were all over the place and half the primer pockets were loose after one firing! Have also heard similar results with Winchester brass (new stuff)
    gary
     
  7. loaders_loft

    loaders_loft Well-Known Member

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    One other thing, if your brass has Been exposed to high pressures the primer pockets may be loose. If so then dump it and start again with new brass. Long necks may have started the problem but if you trimmed and then continued having problems then it may be loose pockets.
     
  8. Prairie Dog50

    Prairie Dog50 Active Member

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    I can see that what all of you guys are saying makes a-lot of sense. I forgot to mention that this is all once fired brass or brand-new full length sized brass all of which is Winchester. So please by all means correct me if I'm wrong but I don't think its the brass being too long. However somebody mentioned something about the O.A.L. of the cartridge being to long; I think this very well could be a possibility. I have noticed that when using the Hornady O.A.L. set screw type gauge the case that I bought that is drilled out in the back end and meets sammi specs seems to fit into the chamber quite tightly without any wiggle room. Because of this I might have gotten a false reading due to the fact that I thought I had jammed the bullet into the lands when in reality I didn't have the case properly seated with the O.A.L. gauge all the way into the chamber. One other question I have is when measuring O.A.L. with a bullet comparator attachment, is there a rule of thumb as to how much pressure to exert onto the calipers with my thumb??? This could be part of the problem as well. I don't push as hard as I can but I do push past the natural stopping point of the measurement. To me this is a gray area in reloading that is not often covered in the reloading manuals, so as a re-loader who is still learning I guess I'm in the dark on this one.
     
  9. J E Custom

    J E Custom Well-Known Member

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    If you are not sure that you are getting a good measurement with the gauge, try the old way.

    Take a sized case and insert the bullet you want to use, long and very carefully insert it in
    the chamber until the bolt stops(No pressure) then seat it a little deeper .005 to .010 at a time
    measuring COL as you go. when the bolt will close with little or no effort measure the COL and
    subtract .003 to .005 to this dimension because even though you just barely touch the rifling it
    will engrave slightly.

    This will be your "Actual" COL and with this length start by reducing COL by .020 to start load
    develoupment.(Note if the bullet is touching the rifling you need to start at or below minimum
    load data).

    I weight sort all of my brass and end up with several that are out of batch range and I use these
    to make my COL gauges for different bullets and leave them in my die sets (Painted red and with
    no primer). These are set at the final COL that the load performed best with that bullet.

    I always start .020 off the lands and work up in pressure and velocity and when the most likely
    load is found THEN I adjust the COL closer or farther from the lands for accuracy by .005
    increments.

    Just the way I do it to optimize the accuracy, velocity and pressure.

    J E CUSTOM
     
    Last edited: Dec 29, 2010