Mold Material

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Mold Material

Post by seber » Sat Feb 23, 2013 5:29 pm

Why does no one make bullet molds from bronze? It would seem to be the perfect material. High temp, stable tough, easily machined. The only drawback I can think of would be weight. I'm not a machinist, so I could be wrong about the ease of machining.

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Re: Mold Material

Post by mtngun » Sat Feb 23, 2013 8:31 pm

Price, availability, and no obvious advantage over brass ?

The only rectangular bar stock I can find on short notice is aluminum bronze 954. In the as-cast state, the properties are:

Yield strength = 32,000 psi vs. 45,000 psi for 360 brass

Machinability = 60% vs 100% for 360 brass

Thermal expansion = 9 ppm/F vs 11 ppm/F for 360 brass

Bronze can be heat treated to much higher strength but that prolly wouldn't be a good idea for bullet molds.

I have no idea how it would cast but prolly similar to brass.

There are many different bronze alloys so maybe there is something better out there, but 954 seems to be what is available.

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Re: Mold Material

Post by 6pt-sika » Wed Jul 03, 2013 12:40 pm

I have molds in the single or dual cavity design that are made of aluminum , brass , steel and iron . In that size they all work equally well .

I have molds of 4-6 cavaties made from aluminum , iron and brass . And while they all cast nice bullets the aluminum ones without a doubt being of less weight to begin with are by far easier for me to use over long periods of time . I mean just think about running a pair of 5 or 6 cavity steel molds casting lets say 350-500 grain bullets versus the same thing in aluminum molds . True the molds might weight 6-10 less being aluminum which may not sound like alot but over an hour or two with 2000-3000 grains of lead inside , there is a distinct difference fatigue wise !

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