I disagree. Basically, the effects are the same.

But: the expanding gas of the propellant charge has a lot more energy than springs can ever have.
Reasonable. If it wasn't this way, guns would use springs .

Some effects are the same, like how the projectiles will start growing equal gaps between each other as the first one gets closer to the muzzle. Some are completely different, such as how the force the spring can exert is directly related to the distance between the projectiles but not at all related to the length of time from launch. Also, contained springs do not tend to detonate.

The point was more that a bullet does not "block" the barrel, but I would point out that you would be hard pressed to tell if a spring or compressed gas was on the other side of a cylinder you were trying to compress with a steady force.

The fact that you can blow up an enclosed tube with an arbitrary amount of suddenly expanding gas is not particularly relevant.

Fact is you could cheerfully put more explosive more bullet in a gun than you find in a metal storm, and still not have it blow up if the bullet can get out. (see cannon). The limiting factor on a bullet's velocity is not barrel strength, but the recoil. Sure you can build a handgun that fires 7 deagle rounds in .2 seconds. Problem is you break you wrist doing it.

Either you are intentionally confusing the case or you're not very clear on how firearms and firearm design work.

It is usually a non-issue to enforce a firearm to withstand the pressures it's supposed to handle in normal use. Weapons are designed to handle some amount of overpressure, so that a tiny speck of dirt in the barrel doesn't make it blow up. But every bit of extra pressure that the weapon can handle is bought with added weight and cost, so weapons are not designed to handle massive overpressure.

For example, the chamber and barrel of an M16A2 will normally come under a pressure of ~55kpsi when firing M855 ammunition. The US Army high pressure test round for the weapon, the M197 (a 5.56x45mm NATO cartridge), creates a pressure of 70kpsi, which can be enough to cause some .223 Remington (nearly identical in design to 5.56x45mm) weapons to fail, but service M16A2s have to handle that safely. Put a bit more of a slightly faster burning propellant in there to achieve a chamber pressure of 100kpsi, and what you're going to get is bloody hands, ringing ears, and 7lbs of miscellaneous scrap formally known as an M16A2. That's with a perfectly operational weapon with no blockages anywhere.

Whether you want to call the projectiles "blockages" or not, when firing a whole stack of projectiles at the same time out of a Metal Storm weapon, there will be propellant gases stuck in isolated volumes inside the barrel until all the projectiles in front have cleared the muzzles. This means that the propellant behind the last projectile in the stack will have been burning and gasifying inside the barrel for several times as long as it normally would. Hence there's a lot more pressure stuck inside the barrel for a much longer period time than it normally would.

I cannot say with authority that this would be enough to destroy the weapon. All I can say is that in any conventional weapon a similar pressure increase relative to the regular firing pressure levels would more than likely lead to a (catastrophic) failure.

It isn't? And I thought that's about the only thing that is relevant here.

I think you answered your own question there. If you want the gun to be able to fire all of its bullets at the same time it is easy enough to be able to design it to do so.

Yes the gas is trapped, but not for much longer than the gas is trapped behind a normal bullets.

The gas is able to expand even before the bullet in front of it has cleared the barrel as otherwise normal guns would not work.

Even with an explosion on either side of a bullet, the bullet will still move towards the end of the barrel, as only one of the two explosions is fully contained.

Yes, it'd be easy to reinforce the barrel, breech, etc. to insane amounts of pressure. Only that'd make the weapon weigh a ton, hence why no one (and that includes the people at Metal Storm) does so. What they do is make sure the weapon can handle some dozens of percent overpressure. As I said, even for a weapon that's designed to be particularly sturdy, twice the normal pressure will practically guarantee a catastrophic failure.

Once again, if you go by the assumption that the peak pressure in the barrel doesn't increase, then the time the last propellant in the stack burns in the confines of the barrel is multiplied by a factor somewhat lower than the amount of projectiles in the whole stack. That is to say much longer.

Obviously, and the volume it has to expand in is limited by the breech (or in the case of a Metal Storm weapon possibly the projectile behind it) and the projectile in front of it.

As I've attempted to explain several times in this thread, if all the propellant in a Metal Storm barrel stack went off at once, the last projectile in the stack would be 1/Xth (where X is the amount of projectiles in the stack) the way out of the barrel during the time it would normally take for one projectile to completely clear the barrel, and the other projectiles are at even spacing in front of the last projectile. At this point, there's as much propellant gas in that fraction (1/Xth) of the barrel, trapped behind the every one of the projectiles left in the barrel, as would normally be confined in the whole of the barrel.

Unless, of course, you start with the assumption that the pressures are in a sense cumulative and the simultaneous ignition causes the first projectile in the stack to clear the muzzle much faster -- in which case obviously the whole of the barrel is exposed to far greater pressures throughout the simultaneous firing sequence.

Just look at the spring example you used before. When the first ball in the stack comes to the muzzle, the spring behind the last projectile is still confined in (a bit under) 1/4th the barrel volume. Had the last ball been launched on its own with no stack in front of it, it would be close to clearing the muzzle by this time.

Yes, but it will do so much slower than it would do with an explosion on only one side of the bullet. If there was another bullet blocking the explosion in front of the first bullet, then it will move slower yet. Etc.

And BTW, the propellant in these cases doesn't actually explode. Doing so would guarantee a catastrophic failure of the weapon, except with the kind of massive solid steel blast chamber of a gun you proposed earlier.

No, they are talking Aegis as well.

Good point.

I would like to say that while I do not agree with Austere Emancipator about the difficulty of building a metal storm to fire all of its bullets at once, as it is about as effective to have all the bullets come out of the barrel a barrel length apart, I do not see the theory being tested any time soon. Until then I am content to wait and see.

Since you want to play it that way.

They are talking about replacing the current weapon system with a relevent application of Metal Storm. Does that make you feel better? Sheesh.

There are a lot of things that tend to make one wonder about the Thunderbolt, being that it was devised solely to exploit an unrealistic rule rather than represent a realistic firearm. This is about the only real concept I could use to dovetail with the flavor text in the Lone Star sourcebook.

The capacity is low here mainly because that's the way it was in canon, but also because of the way MetalStorm works. You could certainly get more capacity, but you'd either have to make the barrels so long as to be unruly, or add more barrels. Both options seem fairly rediculous to me.

Yeah. If you look at my edited Ruger picture, that break action method is what I had in mind. The "safety lever" is in this case opens the action and there's a pivot point at the front of the dust cover.

Fair enough then. I retract my irritation.