Does WD40 kill primers?

  • Last Post 19 May 2015
John Alexander posted this 17 June 2014

   I have spent as lot of my recent writing effort casting doubt on some of cast bullet shooters cherished beliefs and rules and acting disrespectful to some bits of our time honored conventional wisdom. So when I saw the post below I thought I would paste it here to shake yet another bit of conventional wisdom. 

  The post came in response to another post by “Lee” issuing a dire warning that WD40 was “one of the worst” things for ruining primers.


“Lee, I am going to second zippy's post. Part of my practice routine has been for years to load 5 rounds with completely dead primers out of each 100 loaded. A few years ago I was able to buy a 1,000 empty primer cups from Winchester. After I had used all of these up, now they will not sell me empty cups. So I went about killing some primers. I have tried every concoction I could think of straight WD40 soaked primers for a week that didn't work so I soaked them for a month they are after that month just as good as new. I have tried soaking some as long as 6 weeks in Alcohol and WD40, Mobile 1 synthetic oil and Alcohol, lard, grease (several kinds), hydraulic oil, Kroil, PB Blaster, Nut Buster penetrating oil, anti freeze, and several others as well. All of these treatments and the primers still go bang. The only thing I have found to render them inert is to remove the anvil. For me the old story that WD40 ruins primers is just as zippy said and old wives tale.” Roland     Once again, this shows that it is a good idea to be skeptical and test to see for yourself instead of just accepting something because it sounds logical.   John  

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armalite53 posted this 17 June 2014

John,  After reading this I can only thank my lucky stars that I haven't blown up my trash guy!

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gpidaho posted this 17 June 2014

Maybe I should rethink the practice of burying oil soaked primers along the garden path.  Seems Ive created a roadside improvised explosive device.  GP

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cptuap posted this 17 June 2014

I wonder what plain water will do?

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badgeredd posted this 17 June 2014


John that is a new one. I have thought for years that oil contamination will kill primers...and it seems to me that I remember a reloading manual that stated if one wished to dispose of primers, the primers could be rendered inert by soaking them in oil. Now I have to experiment to find the true answer! I also need to read some old manuals to see if in fact I did read the thing about killing them in a reloading manual.


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corerf posted this 17 June 2014

From wikipedia

Lead styphnate (lead 2,4,6-trinitroresorcinate, C6HN3O8Pb ), whose name is derived from styphnic acid, is an explosive used as a component in primer and detonator mixtures for less sensitive secondary explosives.

There are two forms of lead styphnate: six-sided monohydrate crystals and small rectangular crystals. Lead styphnate varies in color from yellow to brown. Lead styphnate is particularly sensitive to fire and the discharge of static electricity. When dry, it can be readily detonated by static discharges from the human body. The longer and narrower the crystals, the more susceptible lead styphnate is to static electricity. Lead styphnate does not react with metals and is less sensitive to shock and friction than mercury fulminate or lead azide. Lead styphnate is only slightly soluble in water and methyl alcohol and may be neutralized by a sodium carbonate solution. It is stable in storage, even at elevated temperatures.

As with other lead-containing compounds, lead styphnate is inherently toxic to humans if ingested i.e. can cause heavy metal poisoning.

Assuming the primers are as above then your course of action is the sodium carbonate.

All that means is WD-40 does nothing to it but foul it as a spark plug for your cartridge. It still goes bang, but maybe not as hot due to FOULED PLUGS!

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John Alexander posted this 17 June 2014

cptuap, The zippy referred to in had posted earlier that he had tried to kill primers with water and failed.

Edd, Like you that was another thing that I thought I knew and didn't.  It has the same features as some other bits of conventional wisdom that are also false.  It sound “logical” and makes “common sense."

Shooting gurus have been passing various pieces false wisdom down forever and unless somebody test it we pass it on.  We aren't nearly skeptical enough especially if we see it in print.

There were quite a few posts after that one but none challenged his finding by citing contrary results but I don't know if he included all brands of primers in his efforts.


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Duane Mellenbruch posted this 17 June 2014

A couple of careers ago, when I was in law enforcement, we were cautioned to not use WD-40 on the live rounds in our revolvers.  (I told you it was long ago)  Wether it “killed” the primers, or affected the burn rate of the powder, I do not know.  Some had issues, some did not. 

My personal practice would be to change out my carry ammo to keep it relatively fresh and then fire the old stuff for practice.  Perhaps there is a difference between a primer just going bang, and the ammunition performing properly?  If you are only poking holes in paper, it would be embarrassing.  For serious use, well, you set your own priorities.  You follow your own practices.  Duane

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armalite53 posted this 17 June 2014

My mistake seems to be that I've always taken it for granted that statements made in reputable journals, (e.g., reloading manuals) were the result of SOMEONE'S research, not just an “old hunters's tale". It makes me wonder about another rule: Handle the primers as little as possible, preferably not at all. I don't recall sodium carbonate being exuded from human skin, even if the human uses a water softener! 

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corerf posted this 18 June 2014

Ive handled an awful lot of primers. Not nearly as many as most of the forum members here, but a bunch. If they weren't already bad, I couldn't make them go bad, at least so far. I drop em, I drink my coffee and share it with them, I dust them (add dust not subtract), leave em out in the tray for 6 months, etc.

I would imagine that moisture trapped btw anvil and cup (live round situation) would oxide both and cause a mechanical issue, but not a chemical (in any absolute form). The anvils are pretty well made, accurately, and if deformed by some corrosion may not align right or render a squishy blow to the pellet.

In any case, WD-40 and powder dont get along well so whats NOT good for the goose, is likely to be avoided by the gander (unless the gander has joint pain then the WD-40 should be used liberally before bed to mitigate joint pain.

Elbows and Knees!

Another wives tale, any truth to that one??

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Ken Campbell Iowa posted this 18 June 2014

another report that wd-40 doesn't kill primers comes from geof beneze, who hangs out on yahoo's handloaders forum. he tested the idea about 10 years ago and brings it up on occasion of the myth resurfacing.

someone once told me that the best way to render primers safe was to shoot them up ( g ) .


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joeb33050 posted this 18 June 2014

Back during the Indian wars, while proving that I couldn't shoot even a Model 41 accurately, I kept my pistol stuff in an ammo can-including ammo and cleaning stuff. One time I went to the range and found that not one of the 22s in the box would fire. We decided the culprit was an aerosol spray can of oil?/cleaner? that had killed the 22s. From this I ?learned? that oily stuff kills primers. Then there's this:

SHOULDER SET BACK WAS NOT CAUSED BY THE FIRING PIN HITTING THE PRIMER. Some claim that the firing pin fall drives the case forward, driving the shoulder back and decreasing case headspace. Then when the cartridge fires the case expands, gripping the chamber. This leaves the case with the shoulder pushed back, and excess headspace. I have twice fired one case with ~20 oiled = new dead primers in rifles with the extractor removed, and have not yet had the headspace increase. The firing pin didn't drive the case forward. On 11/16/06, I did this test for the third time on the third gun, a Win M70 Target 30/06 Post 64 rifle. I “killed” 26 CCI 250 Magnum primers with Marvel Mystery Oil. (I did this test at home, in the condo.) Put an empty fired case in the gun. Removed the firing pin from the bolt. The bolt closed easily on the case. Made a .004” copier paper patch to fit the bolt face, put it on the bolt face, the bolt would not close with a little pressure. After testing and fiddling and clicking on 26 primers in that one case, the bolt closed easily on the fired case-wouldn't close with a little pressure with the paper patch on the bolt face. Others, including Tom Gray, have increased head clearance with the firing pin striking the primer, but I can't and this is the third time I've done this test.

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John Alexander posted this 18 June 2014

Well Joe's post proves once again that the world isn't a simple place and we should be careful about making absolute statements about thing we think we know. Sounds like Roland should have tried Marvel Mystery Oil in his series of unsuccessful attempts to kill primers.  Isn't it strange that he found that several penetrating oils include Kroil as well as WD40 wouldn't do the trick. My father always swore that Marvel Mystery Oil was great stuff.  Going to have to get another batch. John

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joeb33050 posted this 18 June 2014

Since it's too rainy to shoot, I tried primers.All primers ?fired?.All trial primers made much less noise going off than new primers.Fired 5 cases, 308 win, CCI 250 LR Magnum primersCleaned after each setWD40 5 minute wait, some compound in primers not burnedMarvel Mystery Oil 5 minute wait, some compound in primers not burned MMO 1 hour wait MUCH black stuff in bore, very quietWATER, 1 hour wait, MUCH black stuff in bore, very quietThere were big pieces of black stuff, primer compound?I don't know which would set off a powder charge.

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Chargar posted this 18 June 2014

I am not a science guy and don't test anything. Back about 1965 while a student at Univ of Houston, I had a friend who as a Patrol Officer with Houston PD. WD-40 was new stuff and Houston a very humid place. My friend had the habit of spraying his service revolver every night with WD-40 with the cylinder open. He would then wipe it down and return it to the leather. He never unloaded the sixgun during this time. After a month or two of this, he found out the rounds in the cylinder would not fire, but unsprayed rounds from the same lot did just fine. Others in the HPD has a similar issue and a directive came down not to spray their service revolvers with WD-40.

As stated, I am not a science type, but I have kept WD-40 away from my guns and ammo since that time. I don't know what the truth is or is not, but I just pass this personal experience along.

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John Alexander posted this 21 June 2014

Very interesting, it looks like anecdotes by Duane and Charger and maybe others and a bit of actual testing by Joe have cast some serious doubt on Roland's results that you can't hurt primers with WD40.  Interesting that the folks over on Benchrest Central didn't question Roland's results and the CB shooters here did.  Maybe that's why they all shoot the 6PPC and use the same powder and CB shooters don't.

It seems like we need to start again believing this bit of conventional wisdom about WD40 and primers or at least thinking that we aren't sure.  I wonder what brand of primer Roland had that seemed impervious to WD40 and others all kinds of bad stuff?

This shows that we not only need to be skeptical of the conventional wisdom passed down to us, but we should also be skeptical of  test results debunking the conventional wisdom at least until there are more tests that replicate the tests of the first debunker.  Or tests to support the original CV as in this case.

My limited experience makes me think that most CB shooters aren't very skeptical at all of the CV handed down to them if it seems superficially “logical"-- and especially if it has been in print. However, their skepticism is at a very healthy level (maybe even extreme level) when judging evidence that debunks the CV if it is a time honored rule that they have been following for years and “believe” in.

 An example is the reaction to my testing results indicating that you don't need to sort bullets by weight to shoot 1MOA groups.  Plenty of skepticism there even though it would be pretty easy to run additional tests to either confirm or debunk the debunker"s results.

The human brain is a pretty complicated device.


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RicinYakima posted this 21 June 2014


Also consider that the formula has most likely changed many times since WD-40 was first marketed. As a teen working on rusty farm equipment in Ohio, it was a first class rust penetrant and highly flammable. Lighting a smoke with your Zippo was not recommended with the old stuff on your hands. First person experience here! The stuff in the last 10 years smells the same, but doesn't work as well as the old stuff. I suppose the price of benzene and chlorinated solvents have gone up in the last 60 years. I feel that it has gone the way of Hoppe's #9, great smell but not as effective.


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Chargar posted this 24 June 2014

When WD-40 first hit the market it was consider a miracle in a spray can with all sorts of functions. I found it most useful to spray inside the distributor cap of my 1950 Ford pickup truck when it drowned out when going through water and having it splash into the engine compartment, which was common. It was a real good water chaser.

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billglaze posted this 19 May 2015

Pretty interesting. I am currently working with primers I bought in the 1980's, and can tell no difference in group sizes than I get with contemporary primers. Admittedly the primers have all been stored inside in cool, dry conditions, but, still, 30 years old............... I first learned about the CW idea of primers being killed by any amount of oil, when Phil Sharpe mandated washing your hands to rid yourself of any skin or otherwise acquired, oil. I've followed it slavishly for years, because it seemed to make sense, particularly when told that the Gov't armories “killed” primers with a drop of oil, when they wished to “inert” them. Now, I'm wondering about the whole thing. Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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norm posted this 19 May 2015

I think primers are sealed or waterproofed better now than they were in Sharpe's day.

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