MadSci Network: Engineering

Re: How the small lead shot ( 7 - 8 sizes ) used for shotgun shells are made?

Date: Tue May 29 13:26:04 2001
Posted By: Joseph Weeks, President
Area of science: Engineering
ID: 987371593.Eg

Historically lead shot has been produced in "shot towers."  You can find a 
number of links on the internet to historic shot towers including the shot 
tower in DuBuque, Iowa,
Potosi, Missouri
Baltimore, Maryland,
and Tasmania
Buck Conner provides a very interesting history into manufacturing bullets 
and shot at the following site:
In the article, you also find a clue as to how shot is made today.

Historically, molten lead was dropped through holes in a copper plate in 
order to form shot.  As the lead shot dropped down the tower, surface 
tension caused the lead droplets to form into round balls.  At the bottom 
of the tower, the partially solidified balls dropped into a water bath 
where they were cooled.  The shot was then screened in order to separate 
the shot by size; shot that was out of round was then returned to the top 
of the shot tower to be remelted once again.  The taller the shot tower, 
the larger shot that could be successfully produced, since the larger shot 
needed more time falling to cool.

As implied in Mr. Conner's article, large shot towers can be replaced by 
providing a forced flow of cold air up a shorter tower, the speed of the 
air flow will help to determine how large shot can be successfully 

Modern manufacturers try to protect their manufacturing secrets well.  
However at I found a listing for 
three jobs that help to understand how shot is being produced today; a shot 
dropper ( ), a shot polisher 
and inspector ( ), and a shot 
bagger ( ).  In the description 
for the shot dropper, we learn that he is responsible for controlling the 
temperature of the kettle which hold the molten lead, the rate that the 
molten lead flows out of the kettle, watching for plugging of the shot 
plate and controlling the flow of metal to be melted into the kettle.  The 
shot polisher and inspector operates a glass plate sorting machine that 
separater round shot from out of round shot, screens the shot to obtain the 
proper size, and sends out of specification material back to the shot 
dropper to be remelted.  Lastly, the shot bagger loads the shots in bags 
for shipment.

There may be higher technology methods to produce shot by chopping wire 
into short lengths and machining them into round shapes, but dropping 
molten lead into a stream of cold air is a simple technology that is hard 
to beat.  Thanks for your question.
To get some idea
rop for

Extruding process
Federal Cartritge

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