The Top 40

Comparing the railgun to a firearm is disingenuous.

Compare the railgun to a rocket and the difference is less.

See, the railgun and the rocket accelerate for a period of time.

A firearm never accelerates at all, as the bullet is simply shrapnel from the solitary explosion with no additional propulsion.

Unless I'm dreaming, the conventional bullet accelerates down the barrel, and my 6" barrel allows for more acceleration than a 3" one.

On topic: the high velocity rail projectile is a badass invention. But, it needs a fleet, manned by trained sailors, to get it to the battle. That fleet needs to survive getting there. In effect, you need the whole universe of military arms. Then, blast the spit out of them.

Still, it is a very sweet gun. I'd like 2, please.

You're right about them railguns Casey, and I'll put one right out in the middle of the front yard, but you're wrong about the barrel causing the projectile to accelerate.

A longer barrel will promote accuracy, but I'd like to know the scientific principle behind barrels that make the bullet go faster.

There's an explosion, then from that moment on things like friction and gravity create drag which slows the bullet down.

Unless there is some other force at play here.

There is Ghost. Electromagnetic propulsion is accelerating the projectile the full length of the barrel.
Once the gases from the initial powder detonation expand, the bullet in a conventional weapon is slowing down as it travels the length of the barrel. It is constantly slowing down until it strike a target or succumbs to gravitational forces.

Eventually a railgun projectile also does but one hell of a lot farther down range.

ghost -

"Longer barrels give the propellant force more time to work on propelling the bullet. For this reason longer barrels generally provide higher velocities, everything else being equal. As the bullet moves down the bore, however, the propellant's gas pressure behind it diminishes. Given a long enough barrel, there would eventually be a point at which friction between the bullet and the barrel, and air resistance, would equal the force of the gas pressure behind it, and from that point, the velocity of the bullet would decrease."

From Wikipedia, "Muzzle Velocities"

Also, a longer barrel does NOT necessarily promote accuracy. -

http://www.thetruthaboutguns.com/2013/10/daniel-zimmerman/the-truth-about-barrel-length-muzzle-velocity-and-accuracy/

The sight distance provided by the longer barrel promotes accuracy, and possibly the extra velocity afforded by the longer barrel.

I'm not the best guy on ballistics, but my understanding is that the gasses are expanding for a longer time in the long barrel. Nothing else explains the better velocity, iiac. This means, unless I'm all wet, that the best velocity is achieved by more pressure. Some writers express this as continued velocity, but I could be convinced that it means the dropoff is later compared to the 3 inch barrel.

Isn't there actually a force variation depending on the burn rate of the powder? iow, the "explosion" has a varied rate. Anyway, in application, I agree that everything is a drag on your bullet, including specific pull of gravity depending on your angle from the earth - that is actually important shit, although it sounds trivial.

Back to the ships. idk the weight of this miracle rail gun, but it looks like a heavy cruiser wants it and not a destroyer. I was explaining to my 14 YO son why the carrier does not want one. Then, you have the gravity of history. iirc, the Battle of Leyte Gulf was the biggest, and also the last, surface battle, per se. This makes this gun a support the shores weapon, unless a surface weanie can convince me that it will go so far over the horizon that it will reinvigorate surface tactics. Then, you got to ask yourself, what surface fleet exists with the capacity for a set piece battle?

Percentages force me to say this is a support weapon. Of. Great. Destructive. Power. Pull the Iowa back out of mothballs again?

Ever play around with hard drive magnets? Very powerful. Careful, they'll raise a blood blister faster than you can react. HD magnets glued to a length of wood/steel, can create a makeshift railgun. Again, careful, the acceleration is amazing and can be very destructive. Treat it like a real gun, aimed away from you at all times. There are youtubes out there about this stuff.

A gov't sponsored (unlimited stolen money) rail gun with powerful electromagnets could be a terrifying yet exciting thing to witness. Shoot a volkswagen, with hitlary in it, into the moon.

Ghost,
The railgun works similarly to the electric door locks on a car. I agree that the electromagnetic field will increase velocity as the sabot/shoe goes down the barrel.

Bullets fired from a gun do NOT normally slow down inside the barrel, although they can. When gunpowder is ignited by a primer, it does not all instantaneously burn up. Gun powders burn at different rates, and in most cases not all of it is burned up. We sometimes see a muzzle flash which indicates that gunpowder is still burning after the bullet has left the barrel. Pressure can build inside a longer barrel due to time vs. burn rate of the powder, and the bullet will normally accelerate as it travels down the barrel.

I not only know that all the gunpowder does not burn up, I have seen the evidence every time I sweep the gun range. Usually within the first five feet of each shooting position I can sweep up a significant amount of unburned powder. Once or twice, someone has dropped a match on such sweepings (after hours) and it burns creating quite a bit of smoke. Very interesting discussion above.

I certainly appreciate your service, sir! Happy Memorial Day!

"a bullet loses velocity from the moment the gunpowder ignites and sends it flying."
The bullet accelerates until it leaves the barrel. That's why the Army is producing a six foot longer barrel for the 155 mm howitzer to increase the guns range.
http://theweek.com/articles/615224/army-crazy-new-howitzer