Casting for this would be challenge.

[Pb2au]

I am thinking sizing and gas checking would be difficult too.

http://www.atlasobscura.com/places/project-harp-space-gun-barbados

[novalty]

Pb2au, thanks for posting the link. That is a neat article.

[grampa243]

i think they got the caliber wrong. it should be 50mm and 100mm.

[KCSO]

Naval guns are measured different say a 3" 40 caliber the shell is a 3" and the barrel length is 40 times the shell diameter in length. There for they doubled the LENGTH of the barrel rather than increased the bore size.

[Echo]

+1, KCSO. The original 16" cannons mounted on the pre-Iowa class BB's were 45 caliber, if I remember right.

[dbosman]

Cut down thirty gallon grease drums might work as gas checks.
I wonder if hollow pointing would help?

[Jim]

Somebody's gonna have to start a fund drive for the Three Amigos to make the lube for this.

[TJF1]

Where would you get enough lead to cast
terry

[gsdelong]

Spend some time reading about Gerald Bull. he was a true "mad genius" worked for Sadam Hussein, building a gun that was going to launch VW size shells into Israel. He started working for the US until they supposedly did him wrong. As the story I read went he was assassinated by Mossad. Truly great reading about a Ballistic Genius

http://www.amazon.com/Arms-Man-Gerald-Bull-Supergun/dp/089141438X

http://en.wikipedia.org/wiki/Gerald_Bull