primers hygroscopic?

Discussion in 'Reloading Forum (All Calibers)' started by joecob, Feb 24, 2013.

  1. joecob


    Jul 21, 2012
    Are primers hygroscopic and if so does it significantly effect performance?

    One reason I ask is that I reload in the basement and the washer & dryer are
    down there.
  2. bigedp51

    bigedp51 Guest

    My reloading bench is in the "dry" basement and my primers are stored in a wooden cabinet, and I have never have a problem, even with very old primers. Below is for people with primer hygroscopic phobia, and after reading it I'm going to put a old empty ammo can to work. ;) Because I'm buying in large bulk and have a few bricks to protect.

    Primer Storage
    All the directions say to keep them in a “cool dry place”. One primer engineer I know who is a shooter gets a bit more serious than that. I will pass on to you his instructions/recommendations; I follow them. Buy primers by the case of 5000 and try to get them right out of the factory. As soon as I get them they go into a 20MM ammo can (which will hold four or five cases of primers). As I need primers I will go and quickly open the 20MM can and remove 1000 and close the can as soon as possible. These 1000 go into a 30 cal ammo can until used. I only open this can in the lowest humidity conditions possible: winter or an air conditioned area in the summer. I remove 100 or 200 primers and place these in a plastic bag with a closure type arrangement. I remove the primers, seat them, charge the cases, seat the bullets in as short a time span as is practical. He even recommends if you are going to be hunting etc coat the ends with clear nail polish wiping off the excess on a paper towel will leave the polish in place around the circumference of the seated primer. He then places these in plastic boxes and they go back into another GI ammo can for storage until he goes to the range. [Storing primers in a sealed container like an ammo can is contrary to SAAMI recommendations and is potentially quite dangerous -GAS-]

    Humidity is the worst enemy followed by lubricant contamination. I am aware of one lot of government .308 Match ammo that malfunction investigation showed had oil contamination from a over lubricated machine on the loading line. Another lot was discarded when it was found to have oil in the primer mix that dropped in from a mixer blending the ingredients.

    In the government (military) when misfires occur with a ammunition lot or anything else out of the ordinary a Quality Deficiency Report (QDR) is supposed to be filled out and sent to Picatinny Arsenal for malfunction investigation. I was told by my Branch Chief that the first thing done is to query the world-wide ammo control point as to how much of that ammo lot remains in the system. When the report comes back that there is, say, three hundred to four hundred thousand of that lot, they follow this with a World Wide Destruct Advisory to destroy all ammunition of that lot number remaining in any depot. Regardless of whether it is bad or not. It is cheaper to destroy that to investigate!

    You may have noted that with the exception of match ammo, you have never seen government ammo newer than three years old being used. This is because all the new ammo goes into War Reserves in the ammo storage depots around the world and the oldest ammo is then removed and sent to the troops which is generally three years for some calibers and maybe forty years for others. Remember we went all through WW2, Korea and Viet Nam with WW2 50 caliber ammunition because so much had been warehoused. Not to worry here folks, government ammo stored in its original unopened cans has a MINIMUM expected life of 125 years. The trick is to never open the can until it's time to use it. Once opened and exposed to the air, the shelf life drops remarkably quickly.

    Primers: It Don't Go Bang

    joecob, thank you for asking your question, it made me Google the subject and I learned something about having an unused empty ammo can. :D
  3. Steve Blair

    Steve Blair

    Sep 6, 2009
    Ed, I have followed a very similar procedure for years but use cal. 50 ammo cans. I use resealable bags for working stock and have no primer problems, even on thirty year old examples.
  4. joecob


    Jul 21, 2012
    Thanks Ed. Good link to interesting info. Actually I haven't had a problem in 20+ years.
    I don't put much stock in that however. I could have a problem tomorrow, especially
    if I ignore the advice.

    It does appear, by extension, that exposure to moisture is likely to cause inconsistent
    performance. I will take some steps as outlined to limit exposure primarily for that reason.

    I don't hunt anymore and my primary defense is a revolver so I'm not much concerned
    with a very rare misfire and always exercise extreme caution in case it's a hangfire.

    The mechanical areas of the article, a more likely cause of misfires, was interesting and
    helpful also.

    Thanks again.
  5. jonbearman

    jonbearman I live in new york state,how unfortunate ! Gold $$ Contributor

    Jan 3, 2010
    I have a somewhat damp basement especially in the summer.I have been reloading since 1985 in this basement and have never had but a few duds in all those years and believe they were bad to begin with.I now aircondition the area just for my guns sake.I have primers that are from the 1960's and am using them up as we speak and they still go bang with no problem.
  6. joecob


    Jul 21, 2012
    I hear you Jon. I've had the same experience: NO duds, luck? I am mostly
    concerned with consistant performance. I've heard in the past that they're
    almost impossible to deactivate although when I want to discard a live one
    I soak it with motor oil.

    However I don't let my own or any others experience trump demonstrable,
    logical advice. I've heard too many folks justify unsafe and/or damaging actions
    with "I've been doing this for XX years without a problem". I don't believe that
    applies in this case. It's just a general observation.

    I also notice that manufacturers make no effort to protectively package bricks
    of primers knowing they will sit on shelves for an indeterminate length of time
    in all manner of environment. Most cookies are better protected from humidity.
  7. Rust


    Jan 8, 2005
    I found many uses for one of those food vacuum machines.

    Primers - I don't draw a vacuum since I don't know how the primer material and the primer in general would react to a vacuum. Instead I squeeze the bag done to minimize the amount of air and heat seal the bag. The resultant packs get stored in Rubbermaid storage tubs which will not allow the higher bursting pressures of a sealed metal ammo can should a worst case scenario occur.

    I've also found the vacuum bagger useful for storing firearms, parts and pretty much anything that will fit into the cut to length rolls. Just drop in a vapor corrosion inhibitor for metal parts.
  8. langenc


    Aug 7, 2012

    I store mine in a detached loading shed/workshop. Right now it is 25 deg out there. Couple weeks ago it was -15 (minus 15 F), last summer up to nearlly 95.

    Equip has been there for over 25 yrs. All always go bang..
  9. Outrider27

    Outrider27 Gold $$ Contributor

    Mar 24, 2010
    As possibly the last guy on earth that still has a few Alcan primers and uses them on select pistol loads, I can state that storing primers in sealed containers as discussed above seems to work fine. They would be 42 years old, plus however long the sat on the dealer's shelf.... 8)

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