Le 19/03/2010 03:26, Alain nous fit lire :

> Another thing in favor of copper: it's density is higher than steel or
> iron. Around 5 - 5.5 for iron and it's alloys, about 7.5 for copper if I
> remember corectly. Almost 50% higher.
(for water @ 1)
iron is about 8 (max at 7.8, adding carbon and other might drop it to
6.8), copper about 9 and lead about 11.3
Lead "advantage": toxic; "default": does not hold well under pressure
Now, if you want to play with uranium (non-radioactive/depleted), you
get a nice 18.9, nevertheless it is recommended to stay away of
plutonium (despite its nice 19.8)

Platinum (21) is a bit too expensive, even gold (19.3)... and tungsten
(19.6) is a bit too difficult to manufacture for bullets (well, if it
was really worth it... but it might be too brittle too)

> 
> Copper slide well in a steel barel, while steel tend to grind into the
> barel. It's not only the hardness that mather, but also the different
> crystaline structure of the different metals.

Right. Also iron have a magnetic issue, as well as a rusting issue. (and
as rust make the metal expand... you end up unable to fire)

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