This is getting silly
A railgun barrel is essentially a rectangular prism with a very small caliber tube in the center
There is nothing that dictates it must be a rectangular projectile, nor nothing that dictates a maximum caliber.
All that is required, is that the barrel be composed of two parts (normally rails) with current flowing from one part, through the projectile, to the other part.
The simples way is to use 2 flat rails, and a projectile with two flat faces. Nothing prevents a weaponized variant from having two concave rails and a projectile with a circular cross section.
Also, when all one wants to do is demonstrate the high muzzle velocities attainable, there is no point in using a large caliber.
You mistake crude prototypes showing the concept, for an actual refined weapon.
... shock-sensitive payload. If it's in front, the compressive force will either detonate an explosive payload, or completely deform the thin casing.
*sigh*
Again, the peak pressures on pressure based cannons are higher than those of rail guns. Rail guns exert a constant force, cannons do not, rail guns have really really long barrels (which is why the only current military applications being looked into are ship based), cannons do not.
If you get 2x the velocity with a 4x length barrel, how are you going to claim a projectile that works in the 1/4th length barrel won't work in the long barrel?
Not to mention that these rounds would cost an unreasonable amount for their effectiveness, and like all rail projectiles, melt the rail assembly after every shot.
The projectiles themselves are much cheaper than rockets and missiles.
Replacing the rails after every shot (or I think now they are up to every 10 shots), is another story.
They are working on ways to reduce this. Early gunpowder had problems with barrel corrosion. Early high velocity rounds had problems with warping the barrel after a few shots, etc.
A futuristic weapon may have solved the problems railguns are facing now.
Arcing is the major problem, with the rails melting due to the extreme arcing.
Some things they are working on include a thin layer of "electrolyte paste" coating the projectile, such that current can flow, without the projectile contacting the barrel directly.
Materials more resistant to melting/arcing, etc.
ferromagnetic casing
Note that a ferromagnetic casing is only needed for coilguns. A railgun only requires the projectile conducts current.
unidirectional conductors (such as carbon nanotubes) could work, and because of the directionality, would also help solve the arcing problem, as does keeping the barrel in a near vacuum state.
Need we go over all the problems with lasers currently? I think not, its a game set in the future, that takes a lot of creative license given the future setting.
Irrelevant, non-uniform atmospheric density does not decrease projectile travel time.
I never said it did, however, it does decrease the energy lost by the projectile due to drag.
Terminal velocity at 100,000 feet is a lot higher than at 100 feet.
If you fired a projectile up to 300,000 feet, it would fall really really fast through the thin atmosphere.
It would only be travelling through about the equivalent of 50,000 feet or less of atmosphere at sea level, so in this trajectory (nearly straight up), the energy lost to drag would be about equivalent to the energy lost in a "direct fire" shot 10 miles away.
KE kills would still be viable, even if fired at high angles, as the energy lost due to drag is quite small due to most of the projectile arc being in exceedingly thin atmosphere.
Anyway, as I said, this is getting silly, I will speak no more of the real life limitations of rail guns. It seems exceedingly silly when we have pulse lasers, laser satellites, and huge concrete fortresses in an age of gauss cannons.
EDIT: I just realized the old Angel missile launcher had suspiciously similar stats to this new howitzer...
Well, the Current archangel has stats similar to the old angel. The old archangel had a 25k range.
The biggest difference between what I want, and the Angel/Archangel, is the firing interval.
I want a non-salvo fire T-3 artillery that can fire at least several times per minute.
Currently, Archangels fire roughly once every 30 seconds, to once every 20 seconds, depending on upgrades.
I'd like to see something that fires once every 5-10 seconds depending on upgrades - the old angel wasn't anything like this (nor did it have much splash to speak of).
Speaking to the gameplay, there is only one T-3 artillery turret, and this leads to a race for the already overpowered (in some ways) Rocket/missile line.
Many of the complaints I see online about the Rocket/missile line, is that there are no separate upgrades.
By upgrading rockets, you upgrade: Direct fire weapons, AA weapons, and Artillery weapons.
Same for missiles, and when you add the MRL and seraph, you get anti borg and structure weapons too.
Now look at the cannon line:
The artillery it leads to: mortars, howitzers
Mortars you upgrade separately
Howitzers you upgrade separately
Now they finally threw in AA, and some people don't like that you now get AA upgrades "for free" (consider the MG line, its upgrades don't apply to the AA guns).
If the game doesn't end in a relatively early rush, you can't avoid the rocket/missile line.
Many ignore cannons and gauss completely (its also worth noting how much better missile forts are- their range is ridiculous, and they are AA as well).
I think gauss artillery would make going cannons-> rails more viable over rockets-> missiles.
Though in T-1 to T-2, you would still need to take the side path mortar-> howitzers to compete with ripples - which will always be available before ground shakers, which are really the only howitzers that can compete with ripples on large maps where range matters, unless your early rush stagnated, and you just established a forward position where you can build howitzers (the basic 105mm, not the 155mm ground shaker) within range of their entire base.
Or it could be a "tack on" to the howitzer line, the way the "plasma cannon" is a T-3 "tack on" to the cannon line.
Make the "gauss artillery" line use howitzer upgrades, and have Ground shaker and gauss cannon as a requirement.