Why Are Multi-Barreled Muzzleloaders Inaccurate Despite Aligned Barrels?

[kalkyl]

I was watching this video where they’re shooting an old muzzleloaded ”machine gun” with a barrel for each shot. I’m surprised that it’s so inacurrate. Why does the bullets spread, when each barrel is pointing towards the same direction? I’ve seen muzzleloaders like the ”duck foot pistol” that has multiple barrels pointed in different directions, it make sense that such guns will have a huge spread pattern - but in this case all barrels are pointing in the same direction - so I thought all shots would get beside each other?

 

[DaveE]

You'll want to learn about rifling then. Or why a knuckleball is so hard to hit (or catch) in baseball.
Basically, the airflow around a fast non-spinning projectile is very chaotic and won't necessarily be the same for each of the bullets. This causes them to follow different trajectories.

 

[Mark44]

I was watching this video where they’re shooting an old muzzleloaded ”machine gun” with a barrel for each shot. I’m surprised that it’s so inacurrate. Why does the bullets spread, when each barrel is pointing towards the same direction? I’ve seen muzzleloaders like the ”duck foot pistol” that has multiple barrels pointed in different directions, it make sense that such guns will have a huge spread pattern - but in this case all barrels are pointing in the same direction - so I thought all shots would get beside each other?

The barrels are short, maybe 12" to 16", they have no rifling, and the balls were considerably smaller than the inside diameter of the barrels.

 

[BillTre]

Also, it looked to me like the machine gun moved during its firing.
Its carriage is neither heavy nor secured.

 

[kalkyl]

So if they were to use patched roundballs with a tight fit instead, and mount the carriage rigidly so it can’t move, then the pattern will be accurate and not spread?

Here’s another muzzleloaded gun with multiple barrels.

There had to be some advantage with these guns, that justified their production and use. I thought the advantage was the accuracy and effective range compared to a shotgun pattern, that’s why the ”machine gun” pattern surprised me. If there was no advantage with multiple barrels, a one barreled shotgun is easier to make, less heavy and much faster to reload.

 

[DaveE]

I thought the gun sight was a nice addition; like it really mattered, LOL.

 

[phinds]

So if they were to use patched roundballs with a tight fit instead, and mount the carriage rigidly so it can’t move, then the pattern will be accurate and not spread?

It would be MORE accurate and slighly less spread, but hardly accurate. Did you not understand the comments about rifling?

 

[Mark44]

It would be MORE accurate and slighly less spread, but hardly accurate. Did you not understand the comments about rifling?

Muzzle loaders with rifled barrels are quite a bit more accurate than muzzle loaders with smoothbore barrels, a fact that the British troops with their Brown Bess muskets learned the hard way, early in the Revolutionary War.

 

[Borek]

There had to be some advantage with these guns, that justified their production and use. I thought the advantage was the accuracy and effective range

More like initial rate of fire.

 

[Rive]

So if they were to use patched roundballs with a tight fit instead, and mount the carriage rigidly so it can’t move, then the pattern will be accurate and not spread?

You are thinking about that thing the wrong way. It's intended to be a (very) close range assault weapon.
Inaccuracy is a feature.

It's descendants are the 'trench gun' variations. Not something really accurate either...

 

[phinds]

There had to be some advantage with these guns, that justified their production and use.

Production? Do you have information that they were produced in more than a small number?

Also, no there doesn't. At least not in the way you were thinking, I believe. Sometimes maybe gun manufacturers, but much more often individual gunsmiths, reveled in making curious guns.

 

[gleem]

Also, it looked to me like the machine gun moved during its firing.
Its carriage is neither heavy nor secured.

Exaclty, the relatively short barrels do not need to deflect much to develop a spread. The gun fires laterally in sequence so the last barrel to fire in a row will be the one that is off the most. Additionally the load may have been light since the balls hardly penetrated the board also causing the to drop more before hitting it.

 

[BWV]

So if they were to use patched roundballs with a tight fit instead, and mount the carriage rigidly so it can’t move, then the pattern will be accurate and not spread?

Here’s another muzzleloaded gun with multiple barrels.

There had to be some advantage with these guns, that justified their production and use. I thought the advantage was the accuracy and effective range compared to a shotgun pattern, that’s why the ”machine gun” pattern surprised me. If there was no advantage with multiple barrels, a one barreled shotgun is easier to make, less heavy and much faster to reload.

these guns are oddities and were not used much - for military use, grapeshot from a cannon was more effective

 

[Merlin3189]

It may not have much effect at such short range, but it would be very difficult to ensure equal muzzle speed, due to variations in bullet mass, size of bullet and bore of tube, amount and quality of powder.

I think I remember from way back (so don't take this too seriously), that generally such weapons are not in any case intended to aim at and hit anything. They are used to deny operational access to an area, by filling it with more or less random lethal projectiles. So spread is an important characteristic.

 

[BWV]

I think I remember from way back (so don't take this too seriously), that generally such weapons are not in any case intended to aim at and hit anything.

equally true of smoothbore muskets. The whole point was to get a mass of fire into densely packed troops