I haven't seen mortar rounds made, but I would guess their noses are forged or formed then turned to final dimensions.†
By whatever process they are made in the large military industrial complexes, these pictures show how they are made when you can't invest in custom machines, tooling, and material. You are seeing what happens when you have a bunch of bar stock in inventory and a lathe.
It's the "I need a message queueing system and all I have is PHP" version of a mortar.
Medico is a pressing company and mentions on their web page that they've made over 7 million mortar shells of various types. http://www.medicomfg.com/products.php (In the second picture of the last row, the part held in fingers, that pattern you are seeing is pressed in before the metal is formed into a cup. It provides the fragmentation pattern to get the part to break into a nice even spread of the maximum number pieces that still carry lethal energy into human flesh. Probably a 25mm OCWS round. You could set them for a distance and have them airburst just after they went in a window or over a wall. Looks like the program was canceled. Maybe precision and 4 rounds per second didn't need to intersect.)
By whatever process they are made in the large military industrial complexes, these pictures show how they are made when you can't invest in custom machines, tooling, and material. You are seeing what happens when you have a bunch of bar stock in inventory and a lathe.
It's the "I need a message queueing system and all I have is PHP" version of a mortar.
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† Alibaba will hook you up with Wotech Industrial to sell you forged mortar shell blanks for just such an operation: http://www.alibaba.com/suppliers/forged-mortar-shell-supplie...
Medico is a pressing company and mentions on their web page that they've made over 7 million mortar shells of various types. http://www.medicomfg.com/products.php (In the second picture of the last row, the part held in fingers, that pattern you are seeing is pressed in before the metal is formed into a cup. It provides the fragmentation pattern to get the part to break into a nice even spread of the maximum number pieces that still carry lethal energy into human flesh. Probably a 25mm OCWS round. You could set them for a distance and have them airburst just after they went in a window or over a wall. Looks like the program was canceled. Maybe precision and 4 rounds per second didn't need to intersect.)
1916 video of a press forming large mortar noses: http://www.criticalpast.com/video/65675048466_manufacturing-...