What makes a dud a dud?

[SleazyRider]

I shot up a bunch of 1942 ball ammo last week, and noticed that I'd average about two or three duds per box, and I'm wondering if it's the ammo or a firing pin issue. So I pulled a few bullets, dumped out the powder, and tried firing it with a nail and a hammer. It took quite a few shots before it went bang, but it did eventually ignite. Same scenario using a dud round of modern Core-Lokt .30-06.

So I'm curious about a few things:

1. Is there a manufacturing standard to which manufacturers of firearms and ammo must adhere, that prescribes the amount of firing pin pressure it takes to ignite a primer?

2. Are some primers more resistant to ignition than others, perhaps as a function of their hardness?

3. If a primer does not ignite on the initial strike, does it become more sensitive on the second strike, or does it become more resistant to ignition?

4. Are certain brands of ammo reputed to be hard/easy to ignite? In other words, can a firearm that fires reliably with one brand of ammunition be less reliable (in terms of ignition, not feeding) with another?

This is what it took to ignite the primer with a nail:



As always, I truly appreciate your thoughts and opinions on this!

 

[Fleet]

1. Is there a manufacturing standard to which manufacturers of firearms and ammo must adhere, that prescribes the amount of firing pin pressure it takes to ignite a primer?

If you mean from some standard setting body, I'm not sure if SAAMI has a spec for this or not. There may be internal standards that vary from company to company.

2. Are some primers more resistant to ignition than others, perhaps as a function of their hardness?

Yes, as a function of hardness.

3. If a primer does not ignite on the initial strike, does it become more sensitive on the second strike, or does it become more resistant to ignition?

Can go either way. If the primer isn't seated fully, the initial strike can seat it but not fire it. A subsequent strike may fire it. If it's been seated too hard, the priming compound may be crushed between the primer cup and the anvil, in which case it won't fire.

4. Are certain brands of ammo reputed to be hard/easy to ignite? In other words, can a firearm that fires reliably with one brand of ammunition be less reliable (in terms of ignition, not feeding) with another?

In terms of feeding, yes, but it's nothing to do with brand. Certain bullet styles may not feed reliably in an individual gun, but will in another. If a gun exhibits ignition problems routinely with SAAMI spec ammo, which is what all the commercial stuff is made to, then it's a gun issue, not an ammo issue.

The mi-spec stuff you're using has the hardest primers made. This is due to the design of the guns it was originally intended to be used in (M-1 Garand), which because of the design of its firing pin needs these hard primers to be safe. There have been instances over the years with military pattern semi autos of 'slam fires', wherein the rifle fires before the bolt is fully closed, due to the firing pin not having a spring on it to keep it out of harms way. The firing pin is free to move back and forth without restraint. This can destroy the rifle and injure the shooter. You can easily see this on a Garand by cycling ammo through it, each round will have a mark on the primer left by the firing pin smacking it, just (hopefully) not hard enough to cause ignition. The military figured this out early on, and specced the ammo with a thicker primer cup as a result. M-14 and AR pattern rifles have the same problem.

Incidentally, that 1942 ammo you're shooting will have a corrosive priming compound in it. Make sure you do a very thorough cleaning job after shooting it, or you'll have rust issues very shortly.

Based on you pic, which doesn't show a very deep firing pin indent, you may have a problem with your gun that needs to be addressed. Possibly something like a weak mainspring.

 

[hatchetbearer]

I dont recommend you set primers off with a nail, i did that to a shotgun primer as a teen and it blew about a square inch of skin off my pinky and ring fingers.

 

[rdstrain49]

Sounds like a storage issue to me. Properly stored, ammo should last indefinitely.

 

[SleazyRider]

Thank you, Fleet, for taking the time to respond. I don't know what I'd do without folks like you on this forum.

Your comments regarding the WW2 ball ammo make a lot of sense. Is it possible that a typical modern sporting rifle has the firing pin "oomph" to fire a modern round of ammunition, but not enough to fire the hardened WW2 ball ammo?

And, yes, I clean the corrosive residue away in a manner very similar to my black powder guns---hot water and soap, dry, then a conventional cleaning.

Hatchetbearer, I made a small die on the lathe with a hole for the nail, which allows me to safely ignite the primer. I also wear thick leather gloves and a face shield. My body needs all the help it can get!

Rdstain49, this ammo was stored in sealed metal cans, and looks like the day it was manufactured. I think my mainspring is simply not strong enough to fire some of it, as Fleet suggested.

 

[rcmodel]

The freaking ammo is nearly 70 years old!
Only if you get misfires with that rifle with new commercial ammo do you have a problem woth worrying about.

Unless you have a certified document stating where it has been, and how it was stored all those years, Fogadaboutit.
It's old GI surplus ammo, and old GI surplus ammo almost certainly has been exposed to all kinds of poor storage conditions, extreme heat, moisture, etc. .over the years

You may not go off every time when you are 70 either!

rc

 

[KosmicKrunch]

LOLOLOLOL RC, you crack me up sometimes, I almost spit my coffee when I read that LOL

 

[Jim K]

Yes, primers can deteriorate over time as the chemicals age and are subjected to the environment, primarily heat. Ammo of WWII and before may look good, but there is no way to tell where it has been, or what conditions it has been subjected to. Just FWIW, non-corrosive primers were developed in the mid-1930's prior to WWII, but the Army would not use them for standard ammo because they had not been around long enough to have been proven stable. Nobody wanted to find out in the middle of a war that our ammunition suddenly wouldn't work! So we fought WWII with corrosive primers (which had long been proven stable) and the GI's had to really clean their weapons. An exception was made for the .30 Carbine because the inventor told the Army that corrosive primers would turn it into an awkward club and also because it was considered a secondary and temporary weapon.

Powders can also weaken or fail over time, destroyed in many cases because the acid used in manufacturing was not properly neutralized in the speeded up wartime manufacturing. That acid can also eat away cartridge cases from the inside, causing longitudinal splits in cases where they have been stored on their sides.

Now, that new cartridge that a nail failed to fire. There is a reason firing pins are rounded and rather blunt. A pointed tool, like a nail, can miss the anvil entirely (as that one might have) or can strike such a small part of the primer that it does not ignite. Also, manual blows may or may not be strong or quick enough to fire the primer; if the blow is too light, over too small an area, or too slow, it can just break up the primer compound rather than firing it. I think that is what happened there.

Also note that the so-called "pierced primers" are not the result of too hard a blow or too sharp a firing pin or too much firing pin protrusion. They are the result of a LIGHT firing pin blow, enough to fire the primer but without enough momentum to keep the pressure from blowing a piece of the primer back into the firing pin hole.

Jim

 

[RTMiller]

rcmodel - "You may not go off every time when you are 70 either!"

Nuff said. Keep it dry.