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James,
In “Letter Re: Advice on Firearms Caching”, Mark J. wrote “Should I simply use a Hot Hands hand warmer inside the mylar bag and then another one inside the PVC tube? I should not have to worry about moisture if it is vacuum sealed? right? “

Well, no–regardless of the chemicals in the heater. Putting any temporary heat source in a sealed container may actually cause corrosion or water damage that wouldn’t have happened before.

This is why:
Heating air does not remove moisture from a confined environment; it simply increases the air’s ability to absorb moisture from other objects in that environment. That sounds exactly like what we want–except, this only lasts as long as the air stays warm. If the warm, moisture-laden air isn’t moved out of the environment, when that air cools back down it will no longer be able to hold the extra moisture, and the moisture it was holding will condense back out of the air–probably as droplets on the surfaces within the container. The galvanic action that causes corrosion is especially strong on the edges of formed water droplets, and is often why we see pitting of metal surfaces.

When using heat to remove moisture, either the heat must stay on, or the moisture-laden air should be able to circulate away from the item(s) being protected before the air can cool. Folks often think of the warming dehumidifiers used in gun safes–these work for two reasons: much of the warm, moisture-laden air is circulated out every time the door is opened, and when the door stays closed, the heater keeps the environment constantly warm.

These principles are true for any sealed environment, whether its a PVC tube or a CONEX shipping container.

Thanks, – Britt (A Mechanical Engineer with experience in the HVAC industry)

Did you ever wonder just how waterproof your ammunition is?  Over the years I’ve seen ammo stored in everything from cardboard boxes in the attic to sealed ammo cans in the basement, to fruit jars in the refrigerator.    Case corrosion and propellant degradation can occur as a result of exposure to elements, oxygen, and extreme fluctuations in temperature and humidity.  Think of the times when both you and your ammunition were exposed to the elements…wouldn’t it be nice to add one more layer of reliability to your primary weapon system – by ensuring waterproof reloads?  Okay, I’m not going to go into the basics of reloading…just going to talk about a few of the evolutionary steps I’ve taken to ensure that my reloads work as intended.

Being a re-loader of metallic cartridges for some time, I finally decided to conduct an un-scientific experiment of various ammunitions’ ability to remain viable after being underwater for 48 hours.   From a long-term storage and use perspective the military has some of the best ammunition around.  U.S. Military small arms ammunition is mostly produced today in the Lake City Army Ammunition Plant in Liberty, Missouri.   M193 55 grain Full Metal Case (FMC) 5.56 ball, M855 62 grain FMC ball, M85 7.62, 9mm ball, etc – all have bullets and primers sealed during manufacture.  Further, the primers are ‘crimped’ to ensure a better seal and avoid any possibility of the primer dislodging during firing and potentially injuring the operator, damaging or ‘jamming’ a weapon.   A spent primer in the lower receiver of the AR-15/M16 family of weapons can find its way under the trigger group, and prevent the full range of trigger travel required to fire the weapon.  In a serious situation – this could be a life-ending malfunction.  

Since most of us can’t afford to purchase the full amount of military grade small arms ammunition we might like to stock for future ‘famines’ or any other reasons,  we’ve turned to reloading.   Or, it could be that you have non-military calibers in your fleet that you re-load and wish to maintain.  All center-fire rifle and pistol ammunition can be reloaded as long as it’s ‘boxer’ (not Berdan) primed.  Boxer primed simply means one priming hole in the center of the cartridge base.  Berdan primed cases have two or more small holes (off center) and standard reloading dies can’t ‘punch’ the spent primers out through the bottom of the case.  Most steel cased ammunition from overseas is Berdan primed.  It varies widely in performance and quality, but generally it’s decent for long term storage, probably water-proofed to some degree by sealer or total case ‘lacquering’.   When you can find it cheap it’s fine for long term storage and ‘shoot it and leave it’ applications.   One of the hazards commonly associated with lacquered cases is build-up of the lacquer material in the weapons chamber.  This usually occurs only when the weapon gets hot through rapid-fire sessions.  The lacquer can melt in the chamber, then cool and harden – potentially causing a fail to chamber, or more likely, a failure to extract.  This is more common in weapons that don’t sport a chrome chamber, but it can occur with any of them.   Accuracy of overseas military surplus ammunition is generally man-of-angle but nothing close to what a determined re-loader with some patience can achieve.   I’ve stored some of the mildly corrosive Wolf and Norinco ammunition for well over 30 years, with no degradation to reliability.  Is it as good as brass-cased, US military grade ammunition?  Absolutely not – but it beats the heck of throwing rocks and falls into the ‘good enough’ and ‘grateful to have it’ and ‘serviceable’ category.  However, the vast majority of military ball is just that – full metal jacket – and if you want to load hollow points, match bullets, etc you can exercise this option and still build reliability into the products.

Moisture and oil are the two biggest killers of smokeless powder and primers.  Avoid any exposure of oil to the inside of the cartridge case, powder and especially the primers.  The more cautious reloader keeps all primers in sealed ammo cans, with desiccant, in a cool and dry environment until loading time.    When I purchase primers and powder, I mark the year and the month of purchase, loading the oldest first.  During reloading I only handle individual primers with tweezers – never my greasy fingers, lest I inadvertently contaminate the primer with traces of oil.  This author has also started sonic cleaning his brass (after tumbling and de-priming) to ensure that no foreign substances are lucking inside the case.  For this I’ve settled on a cheap cleaner from Harbor Freight Tools, and about 3 tablespoons of Citranox per load.   I can usually get two to three baskets of brass cleaned before switching the cleaning solution.  After I pull them from the cleaner, I rinse twice in clean water.  Two successive 5-gallon buckets of clean water do the trick.  Then I dry on 170 degrees on a cookie sheet in mom’s oven until good and dry.

Many of you out there reload military brass, and have encountered the crimp around the primer.  After de-capping, that crimp must be removed in some fashion to ensure that a new primer can be seated without deforming or catching on the remnants of the crimp.  It can be removed through reaming – removing case material in the priming hole at about a 45 degree angle until the little rim left from crimping is removed.  Hand reamers and electric reamers are available from a variety of resources.  However, I’ve over-reamed a few cases in my day with a Black and Decker Drill and large bit.  Due to the lack of precision in my process I learned about primer venting, and sacrificed an AR-15 bolt in the process.  It slowly became obvious to me by looking at my once fired brass.  There were small black holes where gases escaped by the primer.  Shoot an entire 1,000 rounds like I did and you’ll notice a small recessive furrow melted in a perfectly concentric pattern around the firing pin hole on the bolt face.  This was caused by a majority of 1,000 primers venting and melting small pits into the face of the bolt.  I noticed it after the first 30 rounds or so, but decided to just sacrifice one bolt rather than many. It was either shoot them all – or pull all those bullets.

Currently, I prefer the Dillon’s Super Swage 600 for rolling back the crimp on military brass.  It bolts to the bench and simply removes the crimp by pushing it back with a tapered, hardened rod.  It appears more consistent to me and doesn’t weaken the pocket by removing case metal.  Once you’ve done this you now have a slightly tapered pocket just like you find on commercial loads.  However, the lack of a crimped primer makes it easier for moisture to contaminate the primer and powder.  The hotter your loads and the more your load your brass, the looser these primer pockets become.  If you don’t want to take the time to prepare all that brass yourself a source I do recommend is mi-brass.com.  Send an e-mail to Aaron and he’ll get back to you with prices on brass preparation.  He’s very reasonable, fast and honest. 

After a bit of research on the internet I found Midway was carrying Markron Custom Bullet and Primer Sealer in ½ liquid oz packages.   The product information claims that an application of this “will keep moisture out up to 30 days of complete water submersion.”   In order to test my reloads I took 12 rounds of Lake City 5.56 brass, swaged and reloaded them with 55 grain bullets.  I also took 12 rounds of .45 ACP that I’d reloaded with at least once-fired commercial brass and Montana Gold 185 grain hollow points.   I then applied the Markron sealer to the primer as well the exterior of the case where the bullet meets the case mouth.   I was careful not to apply too much around the bullet, especially with the .45 ACP since these rounds head-space off the case mouth.  Although drying time is specified as 5 minutes, I let them dry overnight.  For the ‘control group’ I used the same batch of 5.56 and .45 reloads but without the primer sealer.  I also included 12 rounds of Lake City M855 ball that have been carried a bit, but were as good as new.   All these rounds went into separate coffee cans full of water. There they stayed for 48 hours.  

The results of this layman’s experiment follow:

                 
What was surprising to me was that fully 25% of my small sample of .45 ACP and 8% of the 5.56 that were unsealed failed to fire.  Just to be sure, I went ahead and re-hit all of these primers at least twice.  They were dead as a doornail.  Collectively that’s a 16.6% failure rate for unsealed ammunition.  Placed in a more positive light – that’s a 100% success rate for primers sealed with Markron Primer Sealer.   As expected – the M855 Lake City ball was as tight as ever and never failed to fire.  At this point I decided to test the limits of this primer sealer, as well as search for a ‘local option’ that might be cheaper and still fit the bill.   I settled on Spar Urethane, which seems a bit thick for the application, but dabbed on with a small paint brush and excess removed with a clean rag seemed like a logical choice.  I sealed 15 rounds primer only, and another 15 both primer and bullet. After application I let the rounds dry 48 hours, then submerged in water for 48 hours.  With 30 test rounds of 5.56 reloads, it became apparent that this stuff indeed keeps the water out.    Be advised that all these bullets were also crimped with a Lee Factory Crimp die.  Results were very positive. 

Conclusions:  For water resistance and reliability this author is going to start sealing all reloads, and all factory ammo that isn’t visibly sealed, prior to placing it into storage.  This will help ensure reliability under adverse conditions, less than ideal storage, hunting, or whatever environment you might find yourself in.