What is the advantage of a brass mold over aluminum?

[osteodoc08]

Since heat retention has been mentioned a lot, is there a way to increase the aboility of an aluminum mold to hold heat? This appears to be a problem, especially with small caliber boolits. Perhaps one could machine a cavity into the mold and fix a brass or iron weight to add in heat retention?

Your suggestion, while a novel idea, would likely cause hot spots not to mention issues with different expansion rates and such.

Aluminum is still awesome. All you have to do to maintain temp is increase cadence. It's not really a problem per se, just need to find your rhythm with each mold.

[tygar]

I've never used brass or steel molds. What's the advantage, besides durability?
Thanks!

I flat out prefer iron molds, they cast good quicker, are tough, you can beat them to death & if you keep them oiled they last forever. I have several Lyman & RCBS molds that are well over 40 years old & cast as good as when I got them new. (actually have a couple Lee alum that are almost as old that still work)

I have lots of alum. NOE, ACE, LEE etc. & most are good (all my NOE are excellent), some are lousy(some Lee really suck) & some OK. I have yet to have a small caliber mold work good in alum. For 4 or 6 cavity the lower weight is nice for long casting sessions.

Only have 2 MIHEC brass (he takes way to long to get his molds). They are heavier than steel. They cast good so far but not sure I like the weight, especially with the 4 banger. Also have to be careful with not hurting them & can't just put some 600 steel wool on a bore brush & spin in the cavity to clean up burrs etc like with steel.

Given a choice, iron up to 4 cavity. Alum for 4+.

I also prefer 2 cavity in rifle & 4s in pistol.

For hollow points, getting the pins hot & keeping them hot is an issue with the alum. Once you get it going & pins hot, it works fine.

When you get down to it, I would always prefer steel, just because; but to be honest, for price, weight, & quality, It is hard to beat NOE. I have a bunch of them & they are all great.

[Springfield]

I had a 4 cavity bras Mihec mould and sold it, just to heavy for me. I find aluminum works best for me as I like 4-6 cavity moulds. I have a lot of LEE moulds because the Big Lube BP bullets just aren't made by anyone else that I can find. But all my AR rifle moulds are either NOE, Mihec, or Accurate. My 2 favorite 9mm and 45 acp molds are HM2. So I do my BP blasting bullets with LEE because I have to but all my more precise molds are higher end aluminum. All my HP moulds are Mihec Brass, but only in 2 cavity. I have a few 2 cavity iron molds but don't use them much, and replace them when I can with better aluminum molds. I just can't take the slowness of 2 cav's anymore, been spoiled.

[MT Chambers]

While NOE, Mihec, Mountain Molds, LBT all make nice molds from Aluminum, I still prefer iron or brass. Pretty hard to beat a Saeco mold, or RCBS, Hensley and Gibbs, and for me: most Lymans.

[Elkins45]

There's just something that's really appealing about the smoothness of the cavities in a quality brass mold. I have a few MP brass Cramer molds and a two cavity from Mountain. They all make really beautiful bullets...but if you have arthritis in your wrists then you'd better break out the Tylenol before a long casting session.

[curioushooter]

Is that BHN at casting temp or at room temp. I have a hard time believing aluminum is stronger or harder than brass.

[kevin c]

I have a 4 cav HP mold from MP in brass that is a work of art. I have several 8 cav MP molds in aluminum, and I'm pretty sure each weighs less than the 4 cav brass mold.

The 8 cavity molds quickly produce the large volume of boolits I need. I don't think I could wrangle the 4 cav twice as fast, even if the cadence didn't overheat the mold. I'm sure I couldn't manage a 8 cav brass mold at the same pace as the an aluminum version, if at all.

[bangerjim]

I prefer to cast a LOT of boolits when I am casting! That is why I use 5 & 6 cavity molds only....now mostly in BRASS. My time is far too valuable to mess around with little steel molds that drop only 1 or 2 slugs at a time.

Unfortunately there are a few designs/cals that are only available in 2 banger molds.

[country gent]

I prefer brass moulds for the heat retention and not having to oil or preserve them. I also like the way they cast. An aluminum mould could be modified with brass inserts installed. Here the size of the inserts probably wouldn't be big enough to make a real difference In weight or heat retention as the outer aluminum blocks would still pull heat away. What might work but would require some real machining would be aluminum blocks with brass plates for the cavities. Again blocks size might need increased and custom handles to be made for them. In most blocks with the cavities pins handle grooves and screw holes there just isn't a lot of extra room.

I believe there are better materials for moulds out there, and available. But expense of the materials difficulty machining them and finish, puts them out of range. D-2 ferro tec s7 are used a lot in die cast moulds and are heat / shock resistant and can be hardened but machining would be hard on tooling. Scandium alloys might be useful but cost here puts them out of the market

Possibly a change in handles to a set that screw into the blocks woukd do away with the handle cuts and increased surface area lowering the heat loss. Sort of like removing or filling in the fins from an engine cylinder.

[curioushooter]

The bugaboo about oiling and preserving iron molds is nothing really. Buy a 2500 sheets of VCI paper off Amazon for $20. A lifetime supply. Wrap the mold up in them (lyman use 1, RCBS/SAECO use 2). Put them in a plastic zip bag. Never had any rust develop this way in the corn sweatiest Southern Indiana. No clean up. No trouble. The rust thing is simply NOT a disadvantage to Fe unless you cast on the deck of boat in over tropical saltwater. Storage rust is trivially preventable. All the important parts on a Al mold are made of steel and rust, too if you don't treat them with the same care as iron.

I prefer iron to aluminum (I have never used brass). While it is true you can cast more bullets with AL because of the lightweight, low cost, and propensity to lose heat rapidly, I never can get them to cast keepers right away and I am not a volume oriented person, more of a quality oriented person. Also, I cast outdoors. Only a few weeks a year are the right temp for casting with Al. I can cast with Fe if its over 45 degrees pretty much.

Durability is also important to me. I want a mold I like to pretty much last forever. Al molds, at least Lees, just start of fall apart and/or get sloppy without only a few hundred cast sometimes.

[georgerkahn]

Lots of poster correctly note the WEIGHT issue re brass moulds. For what it's worth, at age 71 I've really come to appreciate this factor, pretty much totally retiring from use all my iron moulds of 6 or more cavities. And, in past few years, pretty much all my (brass) moulds acquired are two-cavity versions.
Regardless, a (imho) great addition to my bottom-pour furnaces is the acquisition of a few of the FREE laminate flooring sample pieces at Home Depot or Lowe's. My Lyman pot had a metal mould guide -- nothing for the RCBS Pro-Melt. Simply stack a few of the samples under the pour spout, to get just the "right" height. The laminate floor samples are "slippery enough" to enable sliding the now-filled mouid out enough to easily turn over, while opening handles after spru-cut, to again make the casting fun!
Note this works only for those using bottom-pour furnaces -- and for those (like me) with them, it sure really decreases strain on wrist and forearm, again enabling 2+ hour casting sessions.
geo

[Crash_Corrigan]

I have a Lee .452 dia. LRN mold that I bought new in '94. It must have cast 50 to 100 thousand boolits. Nothin' more accurate than one of these slobbered with mule snot lube on top of 3.2 gr of Clays powder out of my Taurus 1911 8 shooter. The mold still casts perfect boolits after 25 years of heavy use. I run two 6 bangers at a time. One with .45's and the other .38's and I can go thru a 22 lb pot of alloy PDQ. I just think that if you properly maintain a decent mold they should last many lifetimes. I agree with pretty much all the previous posters but I will say that certain LEE molds are very reasonably priced and provide a best value for your dollar. That Lee pumpkin ball mold owes me nothing cuz I won money with those boolits.

[Petander]

About weight: I'm holding my molds very little as well. I have sort of chronic tendinitis from musical instruments...

There's the support wire under the pot, then my mold moves one foot to rest on the towel, just a tad lower than the pot. The mold rests on the towel ( not wet ) while I cut the sprue by hand, then I open the mold and tap/shake it very lightly on the towel to release the bullets.

To me there is a different joy in casting with nice'n easy custom molds,brass or not. Tendinitis or not - all those cold sprays are very helpful. Yes good molds cost but they make me smile.