On 2011-12-08, Ed Huntress wrote:
On 8 Dec 2011 03:54:06 GMT, "DoN. Nichols"
wrote:
[ ... ]
I've got a copy of _De Pirotechnia_ which includes how to sand
cast a cannon barrel -- as well as the same for a bell. (Of course,
almost everything is called by an obsolete name, making it more
difficult to understand. And the lathes for boring a cannon once it is
cast are interesting, too. :-)
It was an art. For big cannons, they mixed the alloy as they went,
because tin, like zinc, will separate from copper in a melt if you
don't agitate it.
Nasty.
The one bronze alloy that doesn't require stirring is silicon bronze,
which is fairly strong and corrosion resistant, and widely used for
marine hardware. I wouldn't put gunpowder in it for love nor money,
however.
Hmm ... I've got some, but agree that putting powder in it would
be a bad idea.
[ ... ]
"Cartridge brass" (C26000) is 70% copper, 30% zinc.
Of course, the strength comes from the reinforcing of the
chamber, not from the cartridge case material. :-)
I'm not sure what the story is there. IIRC, it's a matter of
compression strength. Cartridge heads tend to part ways with the rest
of the cartridge at around 60,000 psi. I recall this because I once
shot an overheated handload (then wildcat) .25/06 in an '03 action
that, fortunately for my eyesight, had the Arisaka-type recess
modification. It still scared the daylight out of me. d8-)
The pressure first expands the walls, gripping the chamber
firmly, and then excess pressure tries to push the bolt back (or bend
the frame in a revolver), thus leading to head separation.
I'm not familiar with the Arisaka modification, but it sounds
like a good thing that you had it. :-)
[ ... ]
Thanks for all the typing and information,
DoN.
Typing is free, unless it's for publication. d8-)
Remind me not to publish anything other than what *I* write. :-)
Of course -- legally in the Patent world, posting the
information here counts as publication and starts the one year timeout
by which you have to file your application. :-)
Enjoy,
DoN.
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