Once in a while when discussing blown guns, the prospect of a primer in the powder charge is mentioned. I've always wondered HOW such a thing could happen... I just found a way.

Equipment: MEC Grabber 761R circa 1980. Alliant Promo. Fiocchi 616.

While loading some of my first batch of Promo loaded shells, I was weighing charges frequently for consistancy. Operator error (inattention, distraction, old age, lack of intelligence, whatever) resulted in me cycling the press with no shell in station number 2.

Powder dropped of course, but no primer was visible. I 'recovered' from this event in my usual way, namely undo the primer feed chain, catch the next charge of shot in an empty shell, lock the bar to the left, and clear out the shells under construction so as to provide a clear loader for the cleanup.

On the second cycle of the press, the primer appeared. It had been stuck in the powder drop tube, held there by powder packed around it.

This was something of an attention getter.

The 'what if' is obvious.

Yup, 'Ol Murphy' is always around ....!




Best,

Great information Jonesy and thanks for the heads up!!
When reloading you're always thinking how something like this could possibly happen, yet it does. And regardless if it ONLY happens once in a million shells that is one to many.

I wonder how much more pressure is developed with the primer in the powder? I have not heard of this causing a barrel to blow,so I'm curious.

Thanks for the heads up. I try to watch the primer go into the rotating tabel but not all the time. I will check closer from not on.

Regards, Gordon

I think that the proper test gun for primer in powder has to be a K80. They seem to be always blowing up according to posts over at trapshooters.com bbs. .

Just to clarify what the idiot (me) did... since my writing is isn't all that clear...

I forgot to feed the thing a shell, and didn't catch the mistake until cycling the press with a vacant second station. That station primes and drops powder.

The key point, and the learning experience here, is that if you do that the powder drop tube can pick up the primer that was waiting there to be seated in the shell you forgot feed it. It's out of sight in the tube, jammed there by the powder that was dumped and it could very well make it into your next load.

Shotgun, you do yourself an injustice to suggest that you were muddle-headed. You apparently knew to look for "the" primer despite the fact that there would be "a" primer atop the mess or jammed nearby in the index plate after it advanced. Not everyone would notice the presto-chango-whereditgoto after the aggro of the spill. And that Promo is pretty thick salami so might well get a grip on both primer and reprime/drop tube. Thanks for the headsup.

jack

I wonder, too. But if you look hard enough in the published data, you can find instances of a simple primer change resulting in a peak pressure increase of 3,000 psi. Add in the unknown effect of primer ignites powder ignites second primer and I wouldn't be surprised if it were greater than that.

The change in chamber pressure with primer change is due to the powder sensitivity to faster ignition from a hotter primer, not from the primer's addition to the powder gas. Nitro powder burn rate increases dramatically with increasing pressure. A "hot" primer gets the powder going faster which ups chamber pressure initially which ups powder burn rate.

Lacking data, I doubt that a stray primer in the powder would burst a barrel. Does anyone have actual pressure barrel data?

I don't think it's as simple and straightforward as a "hot" primer versus a "cool" primer. I don't believe you can isolate the primer variable from the powder variable. There are interactions between the two that are not intuitive. Such as substituting a R209 for a W209 in one recipe and seeing a major decrease in pressure...make that same substitution with a different powder and see a comparable increase in pressure.

Tough for me to understand how a primer which, unlike smokeless powder, is an explosive, would not contribute to chamber pressure.

Lacking data, I don't doubt anything.

I believer the main charge in a primer is a propellant, not a true explosive.

I believe the stray primer contributes to chamber pressure, but not the difference between normal pressure and a barrel bursting pressure.

There are a couple of "I believes" up there, so I'd really like to see some data. And, I'll have a look at load data to see if there are reversals with "hot" and "cool" primers as to chamber pressure.

As I offered in another thread, send me five guns to blow up, fluid steel, 12 gauge, and I'll do the test. I will load shells with a primer in the powder charge, and shoot them until one shows signs of damage. What could be easier? I will send the guns back to the donors when I'm through and publish the results here. The test will be done scientifically and we'll put this question to bed. Email me at wilmrph@verizon.net and I'll send you my shipping address.

Or, we could put some loads with a primer in the powder charge in a pressure gun and see what the readings are for chamber pressure. Off hand, I'd say that would be easier.

Don, I actually had my post written that way but reconsidered because if I am able to blow up or damage a barrel in some phase of the test, the pressure sensor may be damaged. Another reason we (or I) won't do it that way is that it is too hard to coordinate the loading of the shells and the conduct of the test together with the location of the pressure testing aparatus. If you know of a way to simplify the whole process and also get an unpaid volunteer to do the work, you be sure to let us know.

Well, let's just say "don't do that,it's bad" and leave it at that. Exact pressures arn't really necessary.

Well..... I think I actually did it once upon a time. I was reloading 20 gauge target loads (STS hulls, W-209, AA wad, 15.6gr. Universal Clays, 7/8oz.#8's) for use in an L.C.Smith Field Grade. Loading was done in a Mec 600, no auto primer feed. Several times I caught myself reaching for a primer instead of a wad. It was a marathon loading session, late at night, and I was tired. Not thinking that I had actually gone so far as to drop a primer in the wad guide, I continued on. The next day on the trap line one of the shells produced a report much, much louder than normal. Looking at the gun I noticed a chunk of wood missing from the upper RH stock cheek. I opened the gun (with much difficulty) and found the primer to have been blown- the gas from which no doubt blew out the wood. Everything else seemed normal. Even found the missing chunk of wood in the grass. Upon further investigation I noticed a fresh shell would fall into the the chamber further than it would in the other chamber. That's when I noticed a slight but definite bulge on the RH side of the barrel, right over the end of the chamber.

The previous shot had smashed the clay bird, so I'm reasonably sure there was no wad stuck in the forcing cone. Examination of the previously fired hulls turned up no missing pieces that could have lodged there also. Shaken (but not stirred), I went home. It was later that I remembered the incident of almost dropping a primer into the wad guide and have since come to the belief that I must have done so. Needless to say I dissected the remaining shells from that session- about 600 -only to find nothing but powder, wads and shot. My one brush with disaster gun-wise, and it was enough.

http://www.speer-bullets.com/education/primers.aspx

There are three primary chemical components that create a modern primer. The initiator is a percussion-sensitive primary explosive that will detonate when struck sharply. The fuel provides gas pressure and sustained heat, and the oxidizer provides extra oxygen to support burning in the closed case.

The explosive mix in the earliest primers was mercury fulminate.

The mercury residue in these primers attacked cartridge brass and made it brittle, resulting in case failures.

This situation was remedied in the late 1920's when lead styphnate priming was developed. This primary explosive left no corrosive residue, and meant that shooters no longer had to wash their guns. Today, styphnate priming is nearly universal.

Which primer is "hotter"....R209 or CCI209?

The CCI209 is hotter...

Hull: STS
Wad: Rem Fig8
Powder: 21.0 gr Green Dot
Primer: R209....8,800 psi
Primer: C209....9,700 psi

No, the R209 is hotter...

Hull: STS
Wad: Rem Fig8
Powder: 17.5 gr Clay Dot
Primer: R209....10,270 psi
primer: C209....9,020 psi

No, really, the CCI209 is hotter...

Hull: STS
Wad: Rem Fig8
Powder: 19.3 gr Clays
Primer: R209....9,000 psi
Primer: C209....11,400 psi

Good post, Mike. For sure the styphnate initiator is an explosive. However, there is very little of it and it doesn't contribute enough gas to have a big impact on pressure. The propellant main charge is also small relative to the powder charge, so it is not a big contributor to chamber pressure. Thinking about this, I can imagine that location of the stray primer within the powder might also be an issue. Say we have the stray sitting directly over, or very near, the intended primer, then it might ignite from the first primer firing instead of cooking-off. This would, in effect, give the powder a double dose of ignition and might account for a higher chamber pressure.

Mike, the load data is interesting. "Hotter" probably doesn't exactly describe the way the primer ignites differing powders. Have you looked for a pattern between primers and powder burn rate?

8-b, I'd use a strain gauge glued to a stout test barrel. No big loss if you bulged the chamber.

I load with a P&W 800B. The primer feed tray is directly above the incoming hulls. I have, on occasion, had primers misfeed into the guide rail and drop into hulls. Far as I know, I've always caught this event, but now think I'll rearrange some things.

Another good discussion - thanks all.

Don, in threads where this situations has been discussed, several posters have claimed that the primer in the powder is an impossible situation in several brands and models of loader. The loader with which I have the most experience is the 800B in all four gauges. I have always explained to these people how it could happen with this loader. Thanks for the support. I have also explained how it can happen when using other models of loader. It can happen with any brand or model of loader if a live primer drops off the loading table into a box of empty shells. End of story, except the pressure testing. Sorry, I don't want to request to borrow anyone's test gun to bulge the chamber, which I expect to do before I am through testing. I would rather use the method of shooting defective shells in cheap guns until damage is observed. Send me the guns and I will do the testing and return the guns. wilmrph@verizon.net

I haven't experienced Shotgun's powder drop tube pickup but Bill's scenario has happened to me. Have pywood bins attached to both sides of reloading cabinet, one for hulls on left and one for bag of wads, tools, bottlecaps, sieves, and coke bottle funnels on right. A bit fast on the handle return on a 9000G and the primer (particularly W-209s, less trouble with Remmmys) can be retained and "flung" far and wide by the primer drop tube. I've also had the spring-loaded gate somehow eject a primer from the tray itself despite the plastic cover. Primer tray on right hand, hulls on right hand, yes it can happen as I've found my "lost primer" among them several times. I maintain that loading by multiples of one hundred at a time encourages one to account for the little critters. Shotgun accounted for his; one smart feller.

jack

OK, if you guys don't think I should perform the test, who should do it? I, personally, would like to see this test performed. However, much as other posters question this situation, they don't seem to be interested in seeing the test performed. I'm still interested in doing the test if someone will send me a few guns. I honestly don't have any test guns to use. I will return all guns to donors.

In response to Gary D, 3 years ago, at trap, I had a shot that sounded funny but, I broke the bird. I checked the barrel and the wad was still in there. I would never believed that was possible. Just luckey I looked.

Yeah, we would like to hear a little more about that situation.