Primer Waterproofing Experiment

Just finished loading up some rounds and decided to try a little experiment, on a whim. Here are the results of my rather brief and simple experiment.

4 rounds of .357 mag handloaded ammo, using nickel cases, Federal primers, and 158 gr. XTP bullets were selected at random from a batch I'd loaded. These had a crimp of approximately 1/4 turn. To two of them, I applied clear nail polish around the primer and around the case mouth. I applied one coat, let it dry, and then applied another.

I plunked all four rounds in a glass of water. I also dropped in one factory Winchester .38 SPL JHP round and one Winchester 9mm JHP round. I let them all sit for 48 hours.

Went to the range today and fired them:

-2 .357 Mag rounds with nail polish fired the first time
-2 .357 Mag rounds w/o polish would not fire, even 2nd or 3rd attempt
-both factory rounds fired the first time

So turns out it actually does make a difference! Last canoe trip I took I managed to keep my gun relatively dry but some of the ammo that was in my pocket did get wet. I'd waterproofed it using the method above, and fired it at a later date with no issues, but always wondered if the extra step made any difference.

Have you pulled the bullets and inspected the contents? Maybe re-weigh the powder to see any added water weight.

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No, unfortunately I don't have a bullet puller yet. I would like to do a more scientific experiment and test a lot more types of factory ammo (specifically wondering if factory FMJ is waterproof like factory defensive ammo is), but for now I just did a very basic experiment to see if it warranted testing any further.

Eventually, I'd like to test:

-Factory FMJ vs. factory defensive ammo

-crimped vs. uncrimped rounds

-primers only sealed vs. case mouth only sealed

-whether lacquer affects headspace in autoloaders, whether it can cause light strikes or other problems

I wonder if lacquer paint would be too thin and penetrate where you don't want it to go.

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I used 99 cent nail polish from the drug store, and it is farily thick. I would think you could go thinner so long as whatever you were using wasn't runny.

RC,
I understand your point that most ammo will go off anyway, and I'm not worried about it becoming a dud if it gets rained on either. Like I said, the reason I did this in the first place was because of a canoe trip, where my gun stayed mostly dry but the speedloaders in my pockets were constantly getting wet when I had to get out of the boat. I don't intentionally go walking around in thigh-high water but there are some times when you step in holes or have to go after a runaway boat and don't have time to take the ammo out of your pockets

Now I can't say for sure that those rounds that got dunked wouldn't go off even without nail polish, but I can say that leaving them underwater for any significant period of time does make a difference. When that's all the ammo you have, I think it's worth the extra time waterproofing them just to be sure.

I will say that I certainly don't do this with all my ammo. I would also like to see how many layers of lacquer it would take to start getting light primer strikes, or if ammo sealed in this way affects chambering in autoloaders.