Static electricity question

R

rdmallory

New member
I have been reloading for about 1 year and have primed over 10,000 cases by hand using my RCBS hand primer.

Last night while priming .223 rounds I had a (PMC) primer go off when I was removing the shell from the hand loader. It has been very dry in the house lately so I am guessing it was static electricity. It left a nasty black mark on one of my fingers and I now have an ammo can with 1999 good rounds and one dud.

What does everyone else do to prevent setting off primers with static electricity?

Doug
 
How could static set off a primed case? I'm sure the shell would shield the priming compound from any discharge. Live ammo isn't affected by static electricity.
 
How could static set off a primed case? I'm sure the shell would shield the priming compound from any discharge. Live ammo isn't affected by static electricity.
Click to expand...

A agree, the brass case and the brass primer metal forms a Faraday cage around the priming compound. It was probably something else that set off that primer.

Here's a link to the best faraday cage demonstration I could find.

http://www.youtube.com/watch?v=e4WAuGf6fsY
 
No high primers

None have high primers, and I always seat firmly by hand so I can feel when it bottoms out. What was strange was that it was already seated and I had just reached up to slide it out of the shell holder when it went off. There was no pressure on it at the time. It is mixed brass that has had the pockets hand reamed and ever now I miss one or two that has glue or a crimp not fully removed but I can tell then as it is hard to seat the primer. I have actually crushed a primer that caught the lip up the case I have not seated all the way in and it not gone off.

I dropped it into the ammo can when it went off and I went through most of them trying to find it and all looked normal to me.

They are PMC primers made in Russia but I would not think that would of made a difference.

I no longer hold my finger over the end of the casing when removing it.

Doug
 
That's pretty hard to explain. My best guess would be a hang fire from a defective primer or primer pocket, but I hope someone has a better idea.
 
Found this in another section

"Not a soul touched the gun. There was no dimple in the primer cap. The gun recoiled off the nightstand and landed on the floor, fully cocked and with a new round in the chamber.

I had the shell casing examined in the crime lab. They determined the primer was not fully seated, the powder was cold and static electricity had arched on the cap setting it off."

So if there was an air gap where the primer was seated it has happened before.

Doug
 
Sounds like a lame guess from the crime lab, that's not something they can determine through tests or examination. I can give some reasons why it couldn't have been static electricity:

There is no source of static electricity (like friction) inside an assembled 45 ACP shell.

There is nothing inside a 45 ACP shell with enough capacitance (your body has capacitance, for example) to hold enough static charge to produce a spark.

There's no insulating barrier (like an air gap); any static charge that was generated would be dissipated by the conductive brass before it could build up.

If there were a static charge inside the case, it would take the path of least resistance, this would be the wall of the case. It would not be through the flash hole, through the anvil, and through the priming compound.
 
No static charge differences can exist across a metallic object, the charge will be equal at all points. When any two metal pieces are firmly connected together, such as a primer in a pocket, the primer cup is effectively the same as the rest of the case. No way I can visualize any static charge leading to that detonation, almost certainly has to have been from some other cause. What? Dunno.
 
I now have an ammo can with 1999 good rounds and one dud.
Click to expand...

Why did you toss the one that popped in with the rest? How big of an ammo can does it take to hold 2000 .223 cases? I know a 50-cal can will hold a few hundred '06 but I've never seen how many smaller cases they hold.
 
apparently some people were sleeping in HS science class-- they might want to go back and learn the differences between ferrous metals and non-ferrous metals especially as concerns the conduction of electricity. And if they do not-- I hope they will be haunted by the ghost of the sky police lieutenant who gathered up a box of unfired rounds as souvenirs on the Gila Bend AZ gunnery range, slid them across the seat of his car, and was quickly and terminally chastised when the rounds were set off by---wait for it---STATIC ELECTRICITY---the finding of the accident investigators. I was there.

I use an anti static mat on the top of my bench. They can be had on the internet. The prices are a lot less these days.
 
learn the differences between ferrous metals and non-ferrous metals especially as concerns the conduction of electricity.
Click to expand...

OK, what is the difference? They are both conductive enough to attract a spark, or dissipate a static charge.

ghost of the sky police lieutenant who gathered up a box of unfired rounds as souvenirs
Click to expand...

Do you believe in ghosts? I haven't heard of this incident, but the opinion here has been pretty unanimous that once it's assembled, fixed metallic ammunition isn't sensitive to static electric shock.
 
Sport45

When the thing went off I just dropped it and it ended up in the ammo can with the rest.

I prime and store all my brass in sealed plastic ammo cans because I prime off the loader.

ammo-can-ac35-large.jpg
 
QUOTE: "Learn the difference between ferrous and non-ferrous metals..."

Well many of us try to learn things from this forum without going back to school. So, could someone please explain the difference between a ferrous and non-ferrous metal and give some examples of each type of those metals so we hoi poli will know what the heck you mean?

I don't want to hijack this thread, but this question occurred to me as I read this thread because I'm looking at buying an old antique 12 gauge priming tool for reloading black powder shotshells. Looks like old heavily patina-ed brass, but magnets stick to it. Should I buy it for my intended purpose? Should I worry about whether it's ferrous or no-ferrous?
 
I think they make wheels out of the ferrous metals...

Anyway, all I know about electricity is that it travels the path of least resistance to the ground, and that the switch on the wall being in the off position is no indication that the wires in the fixture aren't flowing with twitchy goodness. Took me a few times to figure that one out, and a few more for it to sink in.

I'm curious for someone to explain the physics of how static electricity can ignite a cartridge. I'm not saying that it can't happen, but it seems highly improbable. It would seem to me that electricity would flow around the case or pistol, as in the other poster's example, and not through the primer cup and case.

Unless there was case lube/dirt around the primer (more resistance) as it was being seated and a little static build up was on the little nubbin that pushed the primer in the case and a finger touching the case completed the circuit. I guess that's possible. It definitely seems more plausible than setting a pistol down for a few seconds and having it discharging it's static load all by itself, enough and in the right place to fire a round. That one sounds more like ghosts up to shenanigans or something.

I would definitely be interested in a little more education on the subject if there is anyone else out there willing to share.
 
In this context, ferrous means iron, or an alloy containing iron.
Examples: cast iron, carbon steel, stainless steel

non-ferrous just means a pure metal or alloy that doesn't contain iron.
Examples: brass, lead, aluminum, titanium, beryllium-copper.

When a steel wrench is dropped on a concrete floor, it can create a spark. This can be a problem if you're working near flammable vapors, or in a combustible atmosphere. Because of this concern, OSHA requires the use of non-sparking tools in hazardous environments. Non-ferrous alloys can be used to make non-sparking tools. This means that they wont generate spark from impact or friction (like a dragging car tailpipe does).

This doesn't mean that non-sparking tools made from non-ferrous metal won't conduct an electric spark; this may be a point of confusion. Both types of metal conduct electricity.

The anti-static mat is a good idea when you may have loose powder, primers, or priming compound on the bench; other than that, I didn't find amamnn's post to be very informative. There is some more discussion of static electricity in this thread: http://www.thefiringline.com/forums/showthread.php?t=391093
 
Another thing to remember is that electricity flows on the outside of a conductor. That's why a stranded wire can handle more current than a solid wire for the same voltage drop. A static arc striking the outside of a cartridge will stay on the outside. To ignite the primer or powder the arc would have to originate inside the case.

In this instance I believe snapping the case out of the shell holder caused a high primer to strike an edge and go off.

Thank you for sharing the story as I have learned from your mistake. I've been putting my finger over the case mouth when taking primed cases out of my Auto Prime. I won't do that anymore.

When the thing went off I just dropped it and it ended up in the ammo can with the rest.
Click to expand...

I probably would have too. It's pretty hard to hold onto something that just bit you.
 
You must log in or register to reply here.
Back
Top