What are the differences between Brass and Aluminum molds?

[TMenezes]

Ok so 99% of my casting expiriance is with aluminum molds. I tried a brass mold when I was just learning to cast and while I loved the quality and looks of the brass I had such a hard time with it. The slugs would stick like crazy and when I finally got them out I would find wrinkles on many of them. I didn't have a pot thermometer at the time so even though I tried going up and down in temperature I was conservative as I didn't want to warp the mold. I want to try brass again but would like to hear from you guys what you do to produce good castings and if you think brass is worth the higher cost.

[Mal Paso]

Get a hotplate and preheat the mold 350-400 degrees. Brass takes a lot of heat compared to aluminum but don't overdo it. Some of us who ran the mold too close to the alloy temp got tinning (alloy sticking to the mold). I'm running 685F PID control, 700F might be a better number for thermostats, WW/Tin. If it gets over 9 seconds from last pour to sprue cut I slow it down and let the mold loose some heat. That may be a place to start and see what your mold wants.

I also turn the shiny brass brown as fast as I can to make a non stick surface.

[Shiloh]

One of the mold makers said brass molds are prone to warping if overheated. Great molds, just don't over heat them.

Shiloh

[dragon813gt]

Brass is heavier but it holds the heat a lot better. Once the mold is up to temp it stays there. If your bullets were wrinkled the mold was still to cold. The more you use the mold and it starts to patina the easier the bullets release.

As far as warping. I don't know how this would happen. You would really have to heat it up to do this.

[W.R.Buchanan]

I have one brass mould and it is my most prized mould. It is a Mihec H&G 503 250gr SWC HP mould. The third boolit that came out of that mould was perfect and all the rest have been as well.

The brass holds the heat better than aluminum due to more mass. IE brass weighs more than aluminum or steel "By volume" ''This really doesn't make that much difference in short fat boolits which seem to cast easier than long skinny ones.

What I really want is 311299 in brass. Nobody will make one.

Randy

[dragon813gt]

What I really want is 311299 in brass. Nobody will make one.

Randy
Did you ask Tom at Accurate to make one?

[44man]

I have used one and did not like it, took more mold heat. Blocks were so large I could not cast fast enough. I was worn out making decent boolits. The thing was also HEAVY.

[DLCTEX]

I have only single cavity brass moulds and they were bought used with some patina on them already. Casting with them has never been a problem. I assume the multicavity moulds are harder to get up to temp, so I would preheat on a hotplate like I do my aluminum and iron moulds.

[Oreo]

I have a theory that mold warping has less to do with over-heating the mold and more to do with uneven heating and cooling of the mold. Eg. dipping the corner of a cold mold into the melt, or dipping a hot mold into water or a wet towel. Just my personal theory though. I've heat cycled all my brass Miha molds to way over lead melting temperature on a hot plate, slowly, and have not yet had any problems.

[CGT80]

I have an MP brass 4 cav 270 grain 45 cal mold. It is very nice and works well, but it is very heavy. I recently got an NOE 5 cav 175 grain 30 cal aluminum. It is also very nice but I like the weight so much better than brass that I don't think I will be buying another brass mold. The brass mold would really wear out my hands, wrists, and arms. I am only 33 and have good strength in my hands. The aluminum mold was much easier on the body. The MP mold is also an HP version, and the NOE is not. I doubt I will go HP again, as I only target shoot. I like fast and easy because I like to make large quantities. 4+ cavity aluminum molds seem like the ticket for me. 2 cav steel molds do fine for me, but I just have to work twice as long. 2 cav brass might be OK for weight.

I have to keep my brass and aluminum molds quite hot. The brass might be more forgiving if it wasn't an HP version, as the pins will usually stick before the brass does. My steel molds (non HP) seem to be more forgiving. The hotplate has been great and I wouldn't do without one now. The PID on my lee 20 pound bottom pour has also made casting much better.

[bbqncigars]

I likes them both. FWIW, Oxpho bluing will give a patina to clean brass instantly.

[dkf]

Have both alum and brass. Like the brass better myself. Of course all my brass molds are MP molds so maybe that has something to do with it. In my experience, brass molds run them hot and give plenty of preheat on the hot plate. Not hot enough you get bullets that stick and wrinkle with not optimal fillout. Especially true with molds that have hp pins.

[collyer]

I like the alum due to the weight. Tom's accurate molds have always done be well. I got a pid from Butternutz and run it at 700 made a great difference in my casting.

[Fernando]

I've gone to brass 2 cavs. and am doing the best I've ever done.
4 hollers are a bit to heavy for long sessions.
I always pick brass now.
Iron is my second pick.

[Walter Laich]

aluminum is my choice for multi cav molds due to the weight difference. I'm mostly cowboy shooting so extreme accuracy is not required

[Fishman]

You will notice several folks mentioning weight. I am a relatively young, plenty strong guy, and I much prefer aluminum. You run 40 lbs of alloy through a mold and by the end of the casting session you think all of the lead is still in the mold somewhere because it gets heavy.

Also, aluminum from the custom mold makers is different than Lee mold aluminum. Much tougher.

[Echo]

I make stages for my pots so the mold sits and slides on the stage during pouring. That way I'm not holding the bugger up weighing 28(seems like) lbs, just lift to and from stage. A few lengths of 1x3, and some smaller ply or waferboard, whatever is handy.

[dondiego]

Echo - Do you have any pictures of you "Stages"?

[CGT80]

I made a bigger platform/stage for my molds as well. It really helped take the stress off my hands and it keeps the mold level so I get a better pour from the bottom spout to the mold. I just clamped the plate on because I didn't know if it would work well. I took the pot apart and flipped the factory rest. The shorter part of it was rubbing on the side of my pretty NOE aluminum mold, which I didn't want scratched. It also put the mold off center unless I twisted it toward the back. The new piece has a hole so that mr drippy doesn't get my platform covered in lead. I haven't used my brass mold with the new platform, but I was using a 5 cav 30 cal 175 grain mold with the new platform.

95577

[captaint]

MP's 2 cav HP molds are my favorite ones to use in brass. The NOE aluminum molds are also very pleasant to use. We have to consider, also, that the NOE alum molds are much better quality than, say, some other alum molds. That makes a big difference.