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I believe it was JTG...

...who brought up Confederate polygonal cavity artillery projectiles. I knew I had one somewhere.
polygonal_cavity.jpg An early attempt to control fragmentation.

6 Comments

 Both of those look like they have a heavy end near the fuze.  Accident or design?  They are a normal Boxer fuse, aren't they?
 

How were those done?  Lost wax? 

Geoff, it might be that, or it could have been threaded for an adapter to take a Bormann.  It looks to be a work in progress with that roughness in the casting where the fuze is place.

 

 
Joe - I was wondering the same thing, how'd they do that?

Geoff - with the Confederates, it was entirely possible they intended to use woooden time fuzes with the shell - which would explain the size of the hole.  The shell on the left has a standard Bormann fuze.  As for the "heavy" part - remember, the fuze wells remove metal, so the balance is better than you might think.
 

Those are sand castings using a 4-5% carbon iron.  That gives a very free flowing melt.  The sand internal is held together with a flour or starch binder.  The fuse hole provided the channel to remove the sand.  The whole mould is assembled in a big box that may hold twenty or more castings. 

 
Ah, yes, Armorer. Thank you for posting this. It is right soothing, somehow, to contemplate the best way to construct a shell so as to most efficiently kill people, compared to contemplating geopolitics in our modern world, which I've mentioned in a comment to a later post than this one.

That (geo-real-politik) ain't the least bit soothing. Scary, rather. As a bandsman, I really would not rather attend any war unless it is conducted with black powder and live music.If I were to get hit, I would insist on being treated with 21st-Century medicine and surgery, of course. (If I could get it. Heh.)

Oh, Augetter, to get back on topic;  Seems to me that that much carbon in the iron will make it brittle, and fracture easily, which is what one wants in that kind of piece.
 
 Well, not so brittle that it fractures in-bore, JTG.  That is distresssing to the crew.