Mechanical deactivation of primers


In several of the european countries (including sadly, Denmark) a cartridge collectors permit is in practice impossible to get. While You may get gun permits for the desired calibers, it still eats into the “allowance” you have, which is 1000 in rifle caliber and 5000 pistol. (even lower for hunters)
Collectors need to pull apart their cartridges, dispose of the powder, fire the primer and put the thing together again.
I do have a lathe and could turn something to hold the case while I fired the primer with for example a modified Mauser bolt, but I think the noise would disturb the neighbours in the other apartments…
Have anybody tried very slowly to press a primer indent and not have it go off? In other words, does a primer have to be struck with a certain speed to go off in the intended way?


Even if you could press the indent into the primer without it firing, I believe you would be circumventing the purpose intended by the law, which is to ensure that the cartridges in your collection have inert primers. A primer with the pressed ident would probably still fire. That being the case, you would be in violation of the law.


I have encountered a similar Problem with cartridges being bought by Japanese collectors in Australia…not only does the primer have to be “inerted” but the case and Bullet must be presented SEPARATELY at Customs on Re-entry to Japan, to “prove” that the cartridges are Inert.

I inerted a series of 6,5, 7.7 Rimless, 7.7 Semi-Rimmed, and 12,7x81SR by the following means:

Inertia Pull the cartridges( the 12,7 was done using an Ammomaster and a hand-lock drill chuck as a collet), dispose of the Powder.
Then I took a Nail-set Punch, rounded off the point to about primer diameter ( 5mm for the 6,5, and 5,5mm for the 7,7 primers; I made a slightly larger one for the 12,7 primer. ( 1/4 inch, if I remember.)

I then placed the case/s in appropriate old barrels, set in a vice, with a Box of old rags at the Muzzle end ( Underneath–Barrel was Vertical); Luckily I have a 12,7 Ho1 Cannon in my collection, and had the barrel handy. In any case, a suitable diameter Steel tube which will hold the semi-Rim will suffice for all the cases except the 7,7 Rimless. One can make up suitable “shell holders” to suit, and fit a long piece of steel tube to them. A Box filled with old rags will do as a “Muffler”.

With the cartridge case in the barrel/tube, I then ( wearing leather welding gloves and a Face mask and my normal HD Workshop apron), apply the Modified nail set to the primer, and “Tap” it with an engineer’s Hammer.
The primer discharges almost soundlessly into the tube and muffler, and the primer has a neat, regular hemispherical indentation across the entire surface of the primer, ensuring that it is “Inert”…the result looks quite professional. Once the case was washed out of any corrosive or tarnishing chemicals, the separate items were labelled in small plastic coin bags ( as used by collectors), in both English AND Japanese Kanji
(My script writing is better than my language skill), and a declaration in English and Japanese ( prepared with the help of my multilingual son)
as to the nature of the parcel’s contents, applied to the outside.

The Collector later told me that the Japanese Customs were impressed by the (correct) Kanji and waved the guy’s cartridges thru without any particular hassles.

But this was a rare case…Aussie Customs ( and US as well) Insist (now) that small items be drilled as well as inerted, and any Fuzes Shells etc, be “Quartered” ( sectioned) in the Larger Calibres ( 20mm and up)…part of a UN-instigated paranoia on Arms Control.
( also local Paranoia as well).

As to the “Pressing” an indentation slowly into the primer cup, this May ( note May) cause the primer pellet to fracture and become inert, but usually the pressure, even slow as you like, will ignite the primer (Friction between cup and anvil)…I have found this when “over-seating” Berdan primers…very often they go off if the collapse of the cup is sufficient…and those that don’t often will mis-or Hangfire…

Of course, this pressing should be followed by a case full of warm vinegar, to kill whatever primer (live) particles are left, and clean out any tarnishing residue if it did go of. The vinegar is then washed out with soapy warm water, and the case dried

If the Law says “Inert” be assured that forensic testing will tell if it is not…then watch out.

Just a few technical observations ( Not a “reloading” prohibited topic)

Doc AV
AV Ballistics Forensic Services
Brisbane Australia.


In Russia we too have law requirements to fire the primer and to drill a case, but we have legal paradox which allows us to avoid problems. The Russian law tells that a cartridge it “set of gunpowder, a bullet, a primer united by a case”. Accordingly, if the cartridge has no one of these components that it not a cartridge. When Russian police has to us claims we ask the police expert to list components from which our inert cartridges consist and to compare them to determination of a cartridge from the law. As a result the police refuses claims to us, but cartridges are taken away all the same as a basic reason of claims by this desire of policemen to take away our collections for itself personally. In other words - us plunder. But you can safely influence primers if previously will pour in a case automobile means for untwisting of rusty nuts and will wait some time.


Dear Moutrage, the use of Auto-oil or Rust-release compound is NOT sufficient to deactivate primers, especially those of more recent manufacture ( WW II and later. The only sure way to de-activate primers without “firing” them, is to use Vinegar and let it sit in the bottom of the case for over night, then wash out with warm water…
The Vinegar will dissolve the Lead Foil seal of the Primer, inside, and then react with the priming compond, deactivating it and making it soluble to be “washed out” with warm water and detergent (soap).

I have seen oil-treated primers fire several days after being “oil treated”…it may take months or even years for oil to deactivate a good primer.
Regards, and Happy New Year

Doc AV


Probably we use a different compound, but Russian compound contains kerosene. Kerosene gets through a foil. At me any primer didn’t shoot


Be careful using WD-40 to deactivate primers. After it evaporates in a couple of weeks, the primers can become live again, but at a reduced power.


[quote=“RonMerchant”]Be careful using WD-40 to deactivate primers. After it evaporates in a couple of weeks, the primers can become live again, but at a reduced power.[/quote]That’s why I gave up taking that route, tried it with some 1938 S&B 7,9 mm, didn’t work…
Thanks all for the advice, I’ll make some sort of clamping device to put on top of a piece of pipe and make a flameproof box lined with rockwool or something, for muffling the noise.


Another collector I know here in the UK (not a member of this forum) uses an old air rifle to deactivate primers. He says he does it by putting the case in a vice once the bullet and powder have been removed. He then places the barrel of the cocked (UNLOADED!) air rifle against the primer and fires. Apparently the pressure of the compressed air is enough to fire the primer by pushing it in against the anvil, but does not leave any obvious signs of deactivation afterwards. If I remember rightly, he did this for large primers such an on .50 BMG and 20mm Hispano. For smaller ones he uses a hypodermic needle to break the foil and inject oil in through the flash hole.


Many years ago when I was in my teens and living at home with parents I used my Mum’s cooker to deactivate primers. Most cookers nowadays have a glass or ceramic-type hob and I wouldn’t recommend this method on a modern hob surface as I suspect it would crack the very expensive cooker.
However, in the days of metal cooker rings, I would pull the bullet, dump the powder, and then stand the cartridge upright on the cooker ring. Turn the heat on and the primer would eventually detonate and neatly remove itself from the case. An upturned tin or similar placed over the cartridge would prevent it from flying around the kitchen - I thought of this after a casing had punched a hole through the ceiling.
I don’t remember the heat ever damaging the case, primer or annulus.
Foolish but very effective.


If your going to try “cooking off” a primer, watch out for the flying primer itself. “Cartguy” can tell you a horror story about all the items a 50BMG primer can go through when ignited.

As far as “oiling” goes, it’s a hit and miss deal, most of the time it doesn’t work permanently however.


Nice article about deactivating primers: … imers.html


If you have a lathe would it not be acceptable to kill the primer using vinegar and then drill a 1/16" (or metric equiv) hole into the primer? This would give a clear indication that the primer has been made safe?


when i m young i trying to deactivate a 9x19 primer (on bxn cartridge) and the primer “poop out” and hit my finger
i wear safety googles and gloves for safety
after i do not touch the primers because is too dangerous to fire without firearm
do no try to oiling esat bloc and ww2 german primers because they have a good proofing sealing and are live even the oil
most of my collection is hunting cartridges that are legal in france and they not require the deactivation of primers