Brass Molds VS Aluminum Mold

[Ernie Rodriguez]

Does a Brass mold produce a smoother(surface) bullet out of the mold than an Aluminum mold?? Since there is a difference in heat transference in brass-can the temperature of the molten lead be slightly reduced??Any other advantages?? Thanks.

[marvelshooter]

Ernie,
Is this a hypothetical question? I looked around a bit and the only brass molds I could find are some antiques. Does anybody currently make them or are you talking about a custom made mold?
Dan

[Ernie Rodriguez]

Dan-As we speak,I am having 2- 4 cavity brass molds made in the exact shape of a H&G 68 SWC FB bullet.It is under a group buy and I have already had a 6 cavity made by same Mold Maker(aluminum) and his molds are superb.I am hoping,that because of the difference in heat transfer,the brass mold is more flexable-as far as changing some of the variables in casting. Ernie

[hill987]

it looks like the brass will warp over time, same for alum. That's why the old brass moulds are old because they quit using them. Steel being the best material for longevity,. I got some old steel Ideal/ lyman that cast some great bullets, if you get the timing right for temp control you can run a long time with great success. There are some companys out west that will make whatever you want in steel for a price

[Levergun59]

Ernie,
I use Rapine mold prep applied with a cotton swab to prevent any sticking. Hypothetically the aluminum should be a little rougher but the mold prep does away with all that. I have never had a mold warp on me in aluminum or brass. The pins or the sprue plates are the usual culprits. The pins can be adjuster and the sprue plates can be cleaned up with a graphite pencil and the graphite makes the sprue plate slick. Molds from Lyman, NEI ect are cast iron, not steel and rust is their only enemy. I don't cast from a pot as the needle acts like a carburator and has a venturi effect allowing gas to form bubbles in the pour. I cast with a 2# ladle with a cast straw built in the ladle. This pours the metal straight from the bottom of the ladle. I overpour each sprue hole allowing the dross to pour back into my cast iron pot. This gets rid of the gas bubbles. A great book to read is by Veral Smith at LBT bullets. My way of casting is a tad slower but the resulting bullets are the equal of any jacketed box of bullets from Sierra or Hornady by weight. Hope this helps
Chris

[oldcaster]

Chris, I think you are correct in thinking that it is easier to pour a higher percentage of perfect bullets with ladle compared to bottom pour but I don't think the needle forms gas. What I think happens is during the constant flow of material past the needle through what is a very small opening around its edges, all dirt that is typically in all alloys, slowly collects on the needle and surrounding areas the same as dirt sticks to the sides of the pot. It then pops loose when enough has accumulated, flowing into the bullet making a cavity. When ladle casting, the ladle is constantly moved and the dirt is knocked loose and doesn't have as much of a chance to accumulate. When cleaning a bottom pour pot after a lot of use, you can see a tunnel of dirt in the bottom where the needle fit into as not all of it winds up going through but is collected instead.

[Ernie Rodriguez]

Sweet Spot-a condition where the mold temperature,lead temperature/mixture and pour rate/method will produce excellent bullets.I have found that with an aluminum 6 cavity molds-if you are careful-a good bullet can be produced. I tried it with 2 -6 cavity aluminum molds-to increase production-and I couldn't work fast enough to achieve this goal. MY conclusion was the aluminum molds shed heat too fast for using two 6 cavity molds for increased production. I recently obtained a 3 cavity BRASS mold-my first one. I can see the difference in heat transfer of the brass. Once the mold is broken in-it produces excellent bullets until the bullets are frosting. The brass mold seems to get up to heat and MAINTAIN that temperature,quite rapidly and I believe this is an excellent quality for a mold.I think an iron mold does the same thing. I ordered my mold from ACCURATE MOLDS and the quality is superb and I got my molds within 2 weeks of placing order.After testing the mold-and taking all the specs of the bullet-I ordered another mold.Cheers

[oldcaster]

Ernie, I think you are right on about the sweet spot. Even moulds from the same manufacturer with the same number of cavities want their own type of casting including speed, pressure pour or not, and temperature. I have an older Lyman 4 cavity .452 that has huge pour holes and it is one of the most difficult moulds to use because if Iwait too long for it to cool after pouring, I need a brass hammer to cut the sprues and if you go too early, I will get a debris smear across the holes that make it necessary to poke them out with a nail every time. I thought about making a different sprue plate for it because I like the mould since it is quick and quality.
I don't have any brass moulds but it would seem that it would be a good material because it is tougher than aluminum but with similar heat conduction and easy to machine. It looks like brass is a good choice for a mould. Your left arm is going to be twice as big as your right though from that four cavity brass. I generally stay with 2 cavity iron just for the weight reason. Maybe some carpal tunnel work and I will like 4 cavities again.