Friday, May 18, 2007

This is why you check, and double check

Everybody knows what those are right?

Sure; it's a primed .38spl case, and some small pistol primers. I'm sure at least half the people reading this have some of each around.

What makes these particular primers special though, is where I got them.

Where you ask?

In my spent primer tray after decapping them; in particular after Mel had decapped them.

We bought a 500ct bag of cleaned and sorted .38spl brass at the last gun show ($0.05 a piece); and were getting ready to load them in preparation for the Texas trip next week. I wasn't happy with how well they'd be cleaned, so I tumbled half of them for an hour, and then Mel started decapping.

Normally I inspect the cases after cleaning and before decapping, but this time with Mel doing the decapping, I forgot entirely. She finished all 250 that I'd tumbled and handed me the try to dump the primers, when I noticed something.

A couple of what appeared to be unexpended primers.

I was... somewhat alarmed and irritated by this; but I thought "well, maybe they're dead"; so I took one, put it in my priming tool, and primed a case. Then I loaded it in the SP101, put my ears on, and fired it into the trash can...

Yup, it was live.

We ended up finding about 15 un-expended primers in the bin. We also went through the remaining 250 "fired" cases, and found that a total of 37 out of the 500 cases had live primers in them.

For those of you who are not reloaders, let me explain the danger here.

When you decap a case, you are applying a hell of a lot of pressure (as much as several hundred pounds) to the case, and to the live side of the primer. With an expended primer this just pops it out. With a live primer though, it may cause the priming compound to detonate.

If the priming compound detonates when your hand is on the lever, that lever could be forced back to the top of it's stroke, breaking your fingers or hand in the process. Depending on how far down your decapping pin is, it could detonate with part of the case wall unsupported and blow out the side of the case(though thats unlikely), flinging high velocity hot brass out the side.

The worst possible thing, would be if a spark or hot metal shaving dropped into the spent primer tray where those 15 live primers are sitting; causing sympathetic detonations in the tray.

That's very very bad.

This is one of the reasons I usually inspect every case before decapping; usually just looking at it when I grab it for insertion into the shellholder... except this time I wasn't the one doing the grabbing, and because it was a change in my process I didn't think of it. It's also why I ALWAYS wear safety glasses when dealing with primers and powder.

I'm also rather irritated with the guy who sold me the brass. I mean, I've had one or two live cases out of 500 before; but never 8%.

Anyway, we safely expended the primers into the garbage can (wheeee, pop gun) re-de-capped them, and then hand inspected each. All was well, so I re-primed them, and they're sitting in my loading trays waiting for Mel and I to finish loading them up.

At least this served as a very graphic demonstration to Mel why you always check, and double check, EVERYTHING when you are reloading.

UPDATE: So I've received several comments to the effect of "Ahhh it's not dangerous, I've done it lots of times"...

You know what, I've done it too; that doesn't make it a good idea, or not dangerous.

I’ll grant you this, a small pistol primer is the smallest conventional primer, so it would do the least damage of any centerfire primer. The pressures generated by a large rifle primer or shotgun primer on the other hand, are quite substantial.

That said, even a small pistol primer can generate enough pressure to dislocate a finger or fling a hand into a cast iron press presuming you weren't prepared for it; and with other primers lying in the tray below it, just one spark is all that would be needed for a detonation. One spark, like a burning hot primer popping out of the bottom of the case it just detonated in (because it is partially pushed out already, and isn’t supported by the shellholder) and flying into the tray for example.

The saving grace here on the impact side, is a compound lever is a lot of force to act against; unless you’re near the top of the stroke. So if it’s a long cartridge, and you’ve set your decapping pin as short as possible, then the only thing that should happen is you getting the crap scared out of you, and maybe having the handle jerked from your hand.

Unfortunately, I have an old fashioned press, with a single point lever…

... and that still leaves the try full of live primers.

So, tell me again how it isn’t dangerous?