Mold Materials: Pros and Cons?

[Bigslug]

My dad started casting 2-3 years ago to feed a replica Civil War Whitworth sniper rifle with a hexagonal bore (can't exactly go out and buy those), and it kinda snowballed from there.

With the exception of that original Whitworth mold (brass), everything we've acquired thus far has been iron. As my horizons expand (notably, finding this forum), I'm seeing a whole lot of aluminum being used and brass being mentioned with some frequency. So I'm curious - what do these different materials do for you?

[longbow]

To be honest, I am a fan of iron moulds.

Pros and cons as I see it:

Iron

Pro: durable, moderate weight, machines well, heats up relatively quickly and holds heat well
Con: iron rusts so has to be protected, lead can "solder" to it but normally not a problem, not as fast or easy to machine as brass or aluminum

Brass

Pro: machines beautifully, doesn't corrode
Con: heavier than iron, softer than iron so somewhat more delicate, seems to need higher casting/mould temperatures to get good fillout, lead can solder to it but normally not a problem, takes longer to heat up than iron

Aluminum

Pro: cheaper than iron or brass (some higher quality aluminums may not be much if any cheaper), machines easily, much lighter than iron or brass, doesn't corrode easily, lead will not "solder" to aluminum, generally heats up faster and easier than iron or brass
Con: softer and more delicate than iron or brass

Having mentioned corrosion, all have steel sprue plates that can rust so all require some protection when not in use.

All can turn out very good moulds that can last a lifetime if used properly... even Lee two cavity moulds for $25.00 can produce great boolits and last a long time if used carefully.

You will see lots of positive comments about Mihec and Accurate brass moulds and they are indeed wonderful moulds but the makers are top notch and produce a very well machined product. The mould finish and fit is second to none and would be in aluminum or iron as well.

If you are talking single or two cavity mould, all are practical but if you are talking 6 cavity mould, iron and brass are a lot heavier than aluminum. For some the extra weight is a consideration.

You will get lots of opinions but I think that any of the materials can make a virtually perfect mould if the manufacturer has high standards.

Just my thoughts.

Longbow

[theperfessor]

Nice summary Longbow. Can't add much to that!

Just got my first brass mold a couple weeks ago and haven't had a chance to use it yet, but I've used ferrous and aluminum molds for years with no problems. They all work and they all have their own unique operating features and characteristics. And you can get good bullets from any of them.

[Mk42gunner]

...They all work and they all have their own unique operating features and characteristics. And you can get good bullets from any of them.

This has been my experience, no matter what the mould is made of.

The best way is probably to keep a logbook of what your individual mould likes; eventually you will get to many to keep all the information in your head.

Robert

[seagiant]

Hi,
The short answer is:IRON! However you will pay more for it as already explained. If I want a tried basic design I go to RCBS first as they are iron and I can usually find one used for a mild discount!

If I need a special design something not usually carried I go to the independent makers,NOE,Mihec,Accurate,Mountain and go with aluminum to keep cost down as you are paying for brand new!

Something I noticed is with my Pro Melt pot I run it about 750 degrees iron or aluminum and it works pretty well. This is with the independent aluminum mold. Lee molds seem to be more finicky to me!