Why do primers fail?


#1

I assume that primers are made by pouring a liquid primer mix into the cup after which it solidifies, maybe by cooling. Does this mean that primers which fail to explode were underfilled/misfilled during manufacturing? Or there is another reason? Is there a pictorial primer (pun intended) of how the process works?


#2

Primers are filled “wet” and then dried. When “wet” the priming mix is safer to handle. When dried, it will perform as designed. Why primers fail is largely due to poor storage conditions. Perhaps someone can explain the science behind this. It is known that German 7,9 Mauser ammunition, properly stored since the 1930’s is as good as the day it was made. Some of this ammunition came in to the US as surplus from Yugoslavia (?) a few years ago and showed no deterioration and very consistant muzzle velocities.

AKMS


#3

Primers are “press-filled” from a wet paste…a pellet of priming compound ( correct weight) is pressed into the cup, foiled, dried in a temperature-controlled room, lacquer sealed, and (in Boxer primers) anvil seated.

The Composition ( in older corrosive primers) can deliquesce ( absorb atmospheric moisture) from immersion, poor storage, or Powder deterioration…look at old US Mil ammo where the primers seem to be “weeping” a whitish (or greenish) crystaline matter around the primer…this is a sign the primer is Kaputt!

One other cause for primer Failure is oil, especially the oils from Guns ( ie, revolvers) and leather belts ( Tanning compound verdigris)…Hence the 1930s development of US brand “Oilsafe” cartridges…to solve a misfire problem in Paytrolmens revolvers , due to the ammo not being cleared from the revolver or belt for long periods of time ( sometimes months or years).

One other ( rare) source of primer failure is Bad seating Practice (cracked pellet,) but that is usually a problem for Over enthusiastic reloaders.

Primers in ammo properly stored, in sealed containers, can survive for over 100 years…I have fired 8mm Kropatschek Black Powder blanks, made in the early 1900s, and they still light up quite well…admittedly the primers are Berdan .250 with quite a large pellet…And they were just in paper wrappers, in wooden crates…must have been stored in a very dry environment for years.

Regards,
Doc AV
AV Ballistics.


#4

As always, Doc AV’s posts are most interesting (at least to me) because of their completeness and wealth of detailed technical information. Few of us will ever match his experience, but we sure can learn a lot from his generous sharing.

Thanks, Doc!


#5

Modern primers seem to be protected from oil. 20+ years ago a bit of oil, particularly penetrating oil left in a case for a couple of days resulted in a primer that was inert or made a very small “poof”. Now I’ve found it hard to inert primers. I use acetone and lacquer thinner for a week or so to try to break the seal and then follow it with penetrating oil. Often works but about 30% of the time when I test it the primer is still alive, though often degraded.

Does anyone have a good, reliable formula for inerting a primer???

Cheers,

Lew


#6

Lew
I agree with you on the 20+ years ago bit.

I section rounds and grind and polish them, not cut them in half like most do.

So a very very dead primer is very very wise and good thing.

I went to a second hand store one time and found a ladies type hat pin, about 8 inches long, and very small in diameter. I use this pin to run through the flash hole into the primer so as to break the seal of the foil or what have you that is there. And then do the penetrating oil.

It has increased big time my number of fully dead primers, not 100%, but a lot more small poofs which is better than BANG!!!

I have talked to several guys that have gotten into this sectioning of cartridges, most don’t do it as I do (but my way is fast and good) and all has agreed that if the primer is of German origins ya just can’t kill it. Stick it with a pin, soak it for a year, they are primers you just can’t kill.
My 2 cents.


#7

I boil the empty case in water and Cascade dishwasher detergent. This will usually disolve the mixture. When the water turns a light yellow you know you are getting there.

Boiling in Cascade is also a good way to clean empty cases. That’s how I do my Benchrest brass, 100 or so at a time. Spread them out on a towel in the beautiful downtown Linden sun for a few hours and they are squeeky clean.

Ray


#8

Thank for the info.
I heard that some primmers on shotgun ammo “commit suicide”, i/e the compound stop working after some years.
Have you hear about it or is it an hurban mith?
Thanks
Martin


#9

[quote=“RayMeketa”]I boil the empty case in water and Cascade dishwasher detergent. This will usually disolve the mixture. When the water turns a light yellow you know you are getting there.

Boiling in Cascade is also a good way to clean empty cases. That’s how I do my Benchrest brass, 100 or so at a time. Spread them out on a towel in the beautiful downtown Linden sun for a few hours and they are squeeky clean.

Ray[/quote]Hello Ray,
I have some all brass empty shotshells with very bad traces of powder (black or smokeless) inside and outside.
Does this trick work about that ?
Or is there a better compound to use ?
Thnaks
Jean-Pierre


#10

JP

Cascade usually will not remove stains or other discoloration. They have to be removed chemically or physically, such as brass cleaner, steel wool, tumbling, etc.

Competition shooters normally don’t care if their cases are discolored or stained. They only care that they are clean. And, cases used in competition generally don’t have time to get discolored before they are shot-out and discarded.

There are commercial cleaning products made specifically to clean cases fired with black powder. I don’t think I’d want to use them to clean collectable cases since the solutions are very vigorous and could ruin the value.

Ray


#11

hello Rey,
I am talking about decoloration but rather solid residues (powder mixed with dust, aso)
jp