[Kadin]

Not from the Earth, no (not easily, anyway). Bull's plan involved using a gun to replace the heavy first stage of a multi-stage rocket.

The Iraqis didn't have the rocket technology (of course, that's why they hired Bull!), which would probably have looked like the US "Sprint" missile, and at the very raw edge of what was feasible at the time.

Interestingly, though, you can get from the Moon back to the Earth using only a gun-type launcher, IIRC. Some lunar mining concepts use this as a way for mined minerals to get back home without uneconomical use of rocket fuel -- typical schemes I've seen tossed around use various electromagnetic launchers with solar panels or nuclear reactors providing the juice. I've never run the numbers myself -- maybe some Kerbal Space Program junkie can figure it out though?

Probably the best use case for gun-type launchers is for orbital transfers of unmanned cargo. There were some neat ideas tossed around in the 80s of having a big satellite or space station with a nuclear reactor serve as a launch platform for small cargo pods, which would lack their own engines. As long as you balanced the number of "up" and "down" pods, you could keep the launch platform in an approximately stable orbit, supposedly. Very hard to do without a big honking nuclear reactor though.