Home Forums Reloading Shotshells "Extra" Primer and High Pressure?

Somewhere on the internet I have read that accidently dropping a live primer into the powder column of a shotshell will cause a catastrophic high-pressure event. Can anyone provide any established data showing that one should be concerned about such a thing happening? Any thoughts on this? Thanks.

DROPPING a primer into powder causes nothing.

FIRING a shell with a loose live primer in the powder mix could be a bad idea.

Well that was enlightening. Please excuse my poor choice of words, but the meaning should have been obvious.

How would you get a primer in the powder? If it did happen i can see the primer detonating instead of burning. But how this very minor secondary explosion would cause extreme pressure is something a ballistic expert would need to answer

I do not see it being a problem at all.

All but the priming compound is irrelevant to the load. If anything, the metal components of the primer will absorb energy (heat)thus reducing pressure. The priming compound of course will add to the pressure so it likely would result in a net increase in pressure. The amount of increase would not be large however.

I would be much more worried about loading technique that allowed such a thing to happen. If that can happen, much worse things could happen much more easily.

A few things come to mind.

First, how would you "accidently" drop a primer into a shell at just the right time to have it fall in after the powder, but before the wad? At that stage in reloading, the shell is pretty captivated and not very accessible from above.

If the primer somehow ended up in the powder bottle (again, how does THAT happen, with a small opening, and no reason to have a primer above the bottle when it's open), and tried to get into the shell during the powder drop stage, I'd think that it would wedge in the bottle opening, or in the drop tube, or in the wad guide fingers.

Worst case, it DOES make it into the shell. At typical shotgun powder charge volumes, the primer would add substantially to the volume inside the hull. When you put a wad and shot in there as well, and tried to crimp it, you would either have a seriously bulged crimp, or a buckled hull. Either way, it should be quickly apparent that something is wrong with that load.

The only other way I see it happening is intentionally, while you ignore all of the steps above.....

The reason for the question is a thread about a shotgun blow-up elsewhere on the internet in which someone offers the "extra primer" as an explanation for the mishap. The matter-of-fact way the theory was presented sounded like it might be an accepted possibility to some. I too am skeptical about it causing a blow-up, at least a blow-up due to the additional energy in the extra primer and subsequent rise in pressure of the round. I suppose the reasoning might be that the primer detonation could cause a standing wave resulting in extremely high pressure. This "detonation phenomenon" has been offered as an explanation for revolver blow-ups when using very light charges of powder; the powder begins burning in multiple locations simultaneously which creates the standing wave. Of course, many knowledgeable persons dispute this theory as being the reason for these blow-ups. Also, there's the warning against using light charges of slow-burning powder in large-capacity cases, which can cause hang-fires and unstable pressures supposedly, but that could well be a different mechanism entirely.

As to how a primer could end up in the powder charge, I can see it happening by dropping the loose primer into an empty hull prior to inserting it onto the loader. Granted, it might take proper star alignment for that to happen, but then, the stars DO align properly on occasion!

I'd worry about a barrel obstruction before a live primer in the powder causing any problems. Still amazes me the infinitesimal few who look down the barrel of their rifle/shotgun before loading up and touching one off. It is usually not a pretty sight when things go wrong in that area.

I'd be more afraid of the primer getting blown back at you when the powder in front of it burns a projectile inside teh shell....