My background... I'm retired US Navy, Electrician's Mate. I worked on the USS Wisconsin's refit in the late 80's and served aboard her in the Gulf War. And I can say with absolute first-hand experience that if they develop rail gun technology to a practical and usable level, they will NOT install them on the Iowa class ships and reactivate them. Why? Power.

Rail guns take gazillions of watts to power. They'd have to completely gut the iowas to put in the power systems required and completely rip out most of the antique power trunks from between tight bulkhead spaces. (Those things were the bane of my existance when we were upgrading her generators and installing cruise missile systems.)

The overhead involved to refit an Iowa with such a power intensive and bulky weapon system (bulk includes power generation and storage) would scuttle any project to do it based on cost alone. It will be cheaper and more practicaly to build a new class of ship around the weapon itself.

The only way the Iowas will see duty again is if they replace 1 or more 16" turrets with a vertical launch system or if they deploy rocket-boosted shells to enhance their range. Otherwise, their time is past as a practical weapon of war.

A point that hasn't been mentioned is the sheer destructive force of an object weighing 2,000lbs at those sorts of speeds. There'd be plenty of collateral damage

To response to the OP, no I don't think so. The reason is that our current gun technology is near the power of a railgun without the expense, yet we still don't use it. The air/missle faction is too entrenched to be dug out.

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Around the year 2000 a gun test was made with current technologies. That allowed the easy construction of 5.2"/65 - 5.2"/190 gun barrels. The former firing a normal weight shell reached a muzzle velocity of 4,000 fps. The latter reached 7,200 fps. That's 3.7 and 6.6 Mach Speed at sea level respectively.

These weapons, which would satisfy the 5-minute requirement for fire support (payload reaching within 5 minutes of being called anywhere), are not adopted despite the fact that missiles and aircraft can't perform anywhere near it's payload speed, range, and flight time. For comparison, a Tomahawk's reported max speed was 860 fps and an F-35's was 1760 fps. It might take ten-thirty minutes for a plane/missile to reach the target area, by which time majority of mobile assets, as noted by simulations, would have fled the area.

Btw, the 5.2"/190 is ~24% longer than a 16"/50 and has much thinner lining. This is mainly due to, much better and less corrosive propellants and much stronger gun barrel materials (1939 gun steel was build to 53,000 lb/in^2 yield strength, we current can make barrels with materials with 215,000 lb/in^2 yield strength).

This along with hyper aerodynamic projectiles (which have been designed before - but not in use due to DoD requirements - more details following) allows ranges in excess of 200+ miles. A 6.1"/52 firing a 121 lb shell can reach 62 miles today with no other assistance. A pure 16"/50 superheavy gun using modern design and propellants could have 40% more muzzle velocity. The kicker is that the shell will land within 5 minutes at practically any range and you can fire in rapid succession.

The reason these hyper aerodynamic projectiles and long barrels are not used is because weapons today must fit pre-existing systems. That is part of the reason why tanks main guns all round have not been upgraded. Designers are forced to work with the limited space and strength of the existing turrets.

However, if we are going to go as far as to refit/recom the Iowas with railguns - then we'll be doing deep enough reconstruction to warrant new turret designs. Railguns would require ripping out the turret as is and potentially replacing the barbette structure.

Now some points. High muzzle velocity is possible with extremely long barrel life. This is due to the vast improvement in explosives and propellants. We have much more powerful propellants that are also less corrosive. Even then, the nature of gun barrel design today allows use to break barrels into multiple sections so if one section is worn, we can just replace one section instead of the whole thing - as in the past - but that's besides the point.

The fact of the matter is, propellants and shell design has already reached the point that extremely high muzzle velocities can be achieved while being much shorter than a Paris Gun and creating much less chamber pressure.

Before anyone says we can't make the gun barrels today, that's completely false. The gun armories have shrunk, but been replaced by automated barrel forging machines. One of these machines could have forged every barrel for every Sherman tank used in WW-II and every 5-inch gun used by the US navy prior to? the Normandy invasion with capacity to spare. That's more than 58,000 barrels within a 29 month period. That's over 2000 barrels per month.

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That's the approximate current state of conventional gun technology today. If that didn't make the USN decide to change, I highly doubt a few railguns or dubious worth (very expensive and power-consuming for only marginal ultility!) would change their minds.

Except you're not going to see a rail gun lob a 2000 lb payload. The rail guns they're using today are using 20kg or less. E =mc^2, and to get 1000kg to do the same thing that they can do with 20kg would take 500 times as much energy. And energy (storage and transmission) is the main limitation of the technology at this time.

Just a note... E=mc^2 is for annihilation, for kinetic energy E=0.5mv^2 should be used? =P

Lockheed-Martin, General Dynamics, etc own missile tech. Every bomb, missile fired makes a ton of money for some politician-owning board of fat cats. For example: During Operation : Cast Lead in which Israel occupied gaza and rooted out the terrorists firing random missile to the tune of 30-80/day, they used 118 Tomahawk Cruise Missiles in 24 hours. Those have a 200k+ price tag, with over 100k in profit. We rushed a bunch over from the US (i.e they unloaded them from the CV task force in the gulf and ordered more.) Lol, in fact, the people who cry about 'foreign aid' or our '439+ military bases' are deluded. We rarely give CASH to anyone. The US Govt buys weapons from US manufacturers, then marks them up and sells them to other nations, or GIVES them to other nations as aid. So for every "dollar" we give in foreign 'aid' we are handing most of it to US arms manufacturers. Those military bases? Lol, those are weapon storage and sales depots. Now, on the other hand, the US military actually manufactures every single canon barrel themselves. How are the fat cats going to make mad money if the US starts making/using those awesome barrels? We can't have that. Why use an AT gun for static antiarmor defense, when we can sell them a bunch of one shot weapons? If they use guns, the ammo is cheap. If they use LAWs etc, then even TRAINING is very very expensive.