Flooded? Your ammo is going to lose ...
This past summer saw unprecedented flooding over large regions of the country. This flooding caused untold property damage and grief to hundreds of thousands of people. Those affected probably lost substantial investments in ammunition and components. Ammunition has some resistance to water for very short periods of time if it's not in very deep water. The good news is there are ways to store ammunition and components that will protect them if you live in a flood risk area.
The explosive mix in primers starts as several dry powder components. These components are mixed together as water is added and you wind up with something literally looking like a ball of cookie dough. This stuff is all mixed together in a blender that for all practical purposes is a heavy duty Kitchenaid mixer with a bread hook on it. The ball of primer dough is then measured out volumetrically into each individual primer explosive pellet, placed in the primer cup and finally the anvil is inserted.
As long as the primer mix is kept wet it's virtually impossible to get it to do anything. At this point in the process you have the exact same assembled primer you purchase, except the explosive mix is wet and won't go off. The primers are then placed in tightly controlled temperature and humidity cabinets to dry. The drier the mix becomes the more sensitive and energetic it becomes.
Primers are tightly controlled for the amount of residual moisture left in the explosive mix. Once the primer mix is completely dried, it's now sensitive to impact and heat and you have your live primer for your cartridge. However, get the primer mix wet again and it becomes virtually impossible to get it to do anything.
If primers are exposed to any water at all, even for a short period of time, they will absorb water and go back to their insensitive state. They can be dried out again and will once again become sensitive and explosive. But without some very expensive equipment it will be impossible for you to tell how much moisture is in the mix. The primer sensitivity and explosive output is strongly determined by it's moisture content.
You really don't know what you're going to get trying to dry primers in terms of their output or sensitivity. Never expose even wet primers to any kind of heat source. That's asking for it. The minute you start disrespecting primers you're going to get burned, literally. If you have primers that have been exposed to water, I would suggest soaking them in oil or powder solvent to inactivate them and dispose them.
The deeper the water the greater the water pressure at the bottom of the water. It's the effect you feel when you dive to the bottom of the deep end of the pool and you can feel the pressure on your ears. The deeper the water loaded ammunition--or any container it's stored in--is exposed to, the higher the water pressure, and the more likelihood of water getting into things. Obviously, the longer things are exposed to deep water, there's more potential for water to seep into things. Deep water, say water measured in feet, will compromise unprotected ammunition very quickly.
Powder Hates Water
The easy answer with loose propellant is to store it in the original container with the lid tightly closed. This will provide adequate water protection for short periods of time for anything other than 20' or 30' of water. Propellant is actually manufactured in large kettles--under water. It's done this way for safety and for the water to provide a means of carrying other chemicals into the grains of nitrocellulose making up the propellant.
The propellant is essentially cooked in a water solution with other chemicals at very specific temperatures and lengths of time. This gets the correct chemical composition to maintain the proper performance. After this cooking phase is done, the propellant grains are dried in temperature- and humidity-controlled cabinets to very exacting amounts of residual moisture. Most propellants are typically dried to about one percent residual moisture and volatiles. The amount of residual moisture and volatiles has a very strong effect on the burn rate of the propellant.
Depending on the propellant and the cartridge a one percent change in the residual moisture and volatiles content of a propellant can change the peak pressure from 5,000 to 10,000 psi, either up or down. The higher the moisture content, the slower the burn rate, and the lower the pressure the propellant will produce, and vice versa. The moisture content can eventually get high enough to prevent propellant burning.
As a side note, this effect is one of the reasons you don't want to expose propellant or ammunition to high temperatures for long periods of time. The propellant will dry out and the pressures will go up. The propellant will also start to chemically break down after long-term exposure to heat, driving the pressure even higher. Sometimes dangerously so. Don't store ammunition in the garage, or your closed car or trunk in the summer.
In loaded ammunition there's a press fit between the primer and the case, and the bullet and the case. This press fit by itself will provide some protection against exposure to moisture and very short durations of being submerged in water. It's enough to prevent any significant performance degradation from exposure to light rain or dew. By short duration of submersion I mean maybe well less than an hour. The shallower the water, the longer it will take for water to seep into the case. The greater the depth and the longer the exposure, more water will seep into the ammunition. At this point it should be pointed out almost all military spec ammunition is waterproofed and will resist exposure to water quite well.
I set up a test to show the effects of water on unprotected ammunition.. The test was very simple, and used nothing more than a 5-gallon plastic paint bucket and tap water. For test ammunition, I used a commercial 9mm 115-grain load. The unsealed ammunition was submerged in the bucket of water, and the same type of ammunition, but with the primers and case mouths sealed, was submerged at the same time.
Hornady's new ammunition waterproofing kit was used to seal both the primers and case mouths of the test amino. Other products such as finger nail polish and blue Loctite, or a threadlocker, also make good ammunition sealants. Don't use red Loctite! The nail polish color that works best is the one your wife likes least; color doesn't matter. Actually, I really like nail polish as an ammunition sealant. It dries very quickly and comes in a lot of highly visible colors. The visibility of the sealant is important because you want to make sure you have it all the way around the primer and case mouth. The flat-type toothpicks work very well for applying the finger nail polish or threadlocker. Check out the tables to see some of the results of this test.
What'd We Learn?
It's pretty obvious ammunition performance will begin to degrade rapidly with even relatively short exposure times to being submerged in water. It also shows it's very easy to make the ammunition virtually impervious to water just by using sealant. When the unsealed ammunition was test fired, it was very dirty, and left large amounts of unburned propellant in the case and barrel. The ammunition that was submerged for 46 hours showed a substantial amount of tarnish on the brass cartridge cases.
There is no doubt if loaded ammunition takes on water, the primer will become less sensitive and energetic and the moisture content of the propellant will increase, making the propellant slower in its burn rate. The end result will be a greater likelihood of misfires and steadily decreasing performance. If things are bad enough, the ammunition won't go off at all or perhaps even worse, you could get a projectile stuck in the barrel.
If you have ammunition that is not waterproof and it has been submerged for anything longer than 1 hour, I would recommend you break the ammunition down or dispose of it. If you are a reloader you can break down the ammunition and dispose of the propellant in your backyard as fertilizer, and fire any primers that will go off, then salvage the cases and bullets. You will likely want to tumble the cases and possibly the bullets because they will become tarnished. A little bit of testing with a chronograph will quickly tell you how bad things are.
What Can You Do?
The entire mess can be avoided by storing your ammunition and components in waterproof cans or containers. Virtually any surplus military ammunition cans have a waterproof seal on the lid. There are also very good commercial waterproof plastic ammunition cans available. Make sure what you buy has a rubber seal in the lid. Anything stored in these cans, with a small packet of desiccant, will survive a substantial submersion in water for several days.
The other thing is to store things in Ziplock bags. I would especially look for the freezer bags because a lot of them have double seals and are a heavier plastic. They will seal out the water better and longer. If as much air as possible is squeezed out of the bag and a desiccant packet is placed inside, anything contained in it will be protected from a good dunking in water. Save the desiccant packs you get in most consumer electronics these days and put a packet or two in each plastic bag or ammo can.
Use the data in this article to give you some baseline for deciding on how bad ammunition or components might be that have been exposed to water. If you're in a flood-prone area, take some steps to protect your investment in ammunition and components. At today's prices it's an investment! As they said in the old days--keep your powder dry.
PHOTOS: CHURCH PITTMAN, INC.
CHART TIME UNDER TYPE WATER (HOURS) VELOCITY (FPS) PRESSURE (PSI) UNSEALED 0 1,120 33,300 UNSEALED 4 997 24,000 UNSEALED 8 944 22,200 UNSEALED 46 515 TOO LOW TO MEASURE WATERPROOFED 46 1,127 33,600 Data for non-water proofed ammunition versus the same ammunition with sealed primers and case mounts, when submerged for various times. Factory 9mm Luger 115-grain ammunition exposed to 13" depth of water.