Theoretical question about double charges.

[Pulp]

This comes up pretty often on the Mythbusters Military and Weapons forum. By double charge I mean a powder charge, a ball or bullet, another powder charge and another bullet. No air gap anywhere in the load. Let's just assume a 70 grain charge and a ..49 caliber patched round ball in a .50 caliber rifle.

Here's what I have pictured in my mind on what goes on internally.

I know (or at least I think I know) that some gas from the first charge will bleed by the first bullet and ignite the second charge. The first ball will also move forward, putting extra compression on the second powder charge. But the second bullet will also begin to move, relieving pressure. The ignition of the second charge would also tend to move the first bullet back, or at least slow it down, increasing pressure on the first charge. Some of this pressure would be relieved through the flash channel of the flint or percussion ignition system.

The question is first, am I even close on my thinking of what is going on inside the barrel; and second, is the gun going to blow up, or is the whole mess just gonna go out the end of the barrel?

I also think that if no gas bleeds by the first bullet to ignite the second charge, then you'd just have 500 grains of powder and bullets going out the end of the barrel.

 

[g.willikers]

Only one way to really find out.
Send pictures.

 

[Ultravox]

And stand way, way back.

 

[Acorn Mush]

By double charge I mean a powder charge, a ball or bullet, another powder charge and another bullet.

What yor are referring to is called superimposed charges. Happened a lot in the heat of battle during the Civil War. I seem to recall reading about a musket picked up after the battle of Gettysburg that had over a dozen charges in the barrel! I wonder what would have happened if the first load had ignited just after the last charge had been loaded? Given the carnage in those battles, the poor guy would have been in a heap of trouble either way.

Hopefully someone with first-hand knowledge will be able to answer your interesting question.

 

[Pulp]

Superimposed is a good word. We know they worked in the Walsh revolver, but that's assuming you fired the top load first.

 

[floridaboy]

I made this mistake more than 30 years ago. There was this duckfoot pistol that I loaded, and then loaded again. Personally, I'm blaming my youth(maybe 20 at the time), and stupidity. The duckfoot failed in spectacular fashion. After the smoke cleared, all that was left in my hand was the grip, frame, hammer and trigger. The trigger had gone all the way back to fully cocked. The barrels and breach-block went thru the car hood that was aimed it. My hand was pretty well bruised and peppered with powder and metal shards. The next day I had blood poisoning, and required a visit to the local hospital. To this day I have powder spots in my hands, wrists and fingers.
This is NOT a double load that I'd reccommend to others.

 

[HKGuns]

Of course it is going to blow up. Just like a double charge of powder in a rifle barrel. Just being BP doesn't make it a lot different.

 

[Acorn Mush]

Hopefully someone with first-hand knowledge will be able to answer your interesting question.

I made this mistake more than 30 years ago. There was this duckfoot pistol that I loaded, and then loaded again. Personally, I'm blaming my youth(maybe 20 at the time), and stupidity. The duckfoot failed in spectacular fashion. After the smoke cleared, all that was left in my hand was the grip, frame, hammer and trigger. The trigger had gone all the way back to fully cocked. The barrels and breach-block went thru the car hood that was aimed it. My hand was pretty well bruised and peppered with powder and metal shards. The next day I had blood poisoning, and required a visit to the local hospital. To this day I have powder spots in my hands, wrists and fingers.
This is NOT a double load that I'd reccommend to others.

DANG Floridaboy. That wasn't exactly the type of "first-hand experience" I was thinking of. Sure glad your injuries weren't worse.

 

[madcratebuilder]

In the early to middle 19th century the term loading doubles meant to load two or more balls on top the power charge, no powder between balls. This was fairly common when shooters were about to encounter hostiles.

There are period books that make reference to this. Intended for fire power not accuracy.

 

[Pulp]

Several years ago Guns and Ammo (I think) had an article on blowing up a T/C Hawken. They use double and triple charges of powder, and up to 7 Maxi-Balls. They would mike the barrel after each shot, and could not find any bulging or cracking.

They finally succeeded by plugging the barrel with a second bullet about halfway down the barrel. That would be expected with any gun.

 

[ElrodCod]

It'll be hard to blow up a barrel with black powder. In an old Dixie Gun Works catalog(I think) they showed a picture of a short piece of barrel (about 10"-12 " long) that was threaded and plugged at each end with a small fuse hole drilled at the midpoint. A plug had been removed and the barrel section was filled w/ black powder & replugged. When the thing went off all of the gas vented through the fused hole with no noticeable effect to the barrel section.