What is the difference between steel and aluminum molds? I see a price difference but is there any working dif? My molds I have now are Lee's.

I've cast with meehanite cast iron molds, steel molds, brass molds and aluminum molds.

When money is no object, I find meehanite cast iron molds to be my favorite. The material seems to be the best at maintaining it's temperature and the they are simply a joy to cast with.

That said, I've never found the material the mold is made from the affect accuracy. And you simply can't beat the value of a Lee six cavity mold. I've yet to find a Lee handgun bullet design that didn't shoot very well, I just haven't tried their rifle molds yet.

Aluminum does require a bit of care as it's the softest material used for molds, use a bit of lube on the sprue plate to keep it from galling and don't slam the mold faces together. You should be able to produce 10's of thousands of bullets from a lee mold.

With my Al molds I have to cast pretty fast to keep the mold at the right temp. I prefer Brass or Iron.

Aluminum moulds are more succeptable to galling at the pins and wear on top from the sprue plate, so they generally require a little more maintenance and lube.

That said, most of mine are aluminum simply because they are lighter and easier to work with that way and thats what the makers choose to extend the life of their tools.

If weight isnt an object, brass is my favorite because it maintains heat well, doesnt need oiled or stored "seasoned" and can be made on the same equipment as aluminum, which makes for a bit of design flexibility.
It isnt as "soft" as aluminum, so it doesnt need as frequent PM.

The responses above mirror my thoughts as well.

I think I have pretty much settled on steel / iron molds as my favorites as well. RCBS are the only ones I currently own though.

My NOE 4 cavity casts great, as well as my RCBS's, but it is a heavy SOB. If I did brass again, I would probably go 2 cavity. If it weren't as heavy, I would probably enjoy it a lot more.

Never been a big fan of Lee and have nothing against aluminum as most of my newer custom designs are aluminum and brass from Accurate Molds.Their mold blocks and sprues are much heavier and hold more consistent heat than Lee designs but of course higher quality comes with additional price.

Guess it depends on how much you want to cast and your budget to accomplish same.

i own about 30 molds, combination of alum, brass, and lyman.
I don't have an issue with lee molds, but they all have their own thing.
lees heat up pretty quick, both good and bad, the others are slower to heat up but seem to handle heat better.
I am kind of hung up on mitech's brass molds these days.
the galling issue with alum is real i think.
But you can get pretty good bullets from a lee from a 25dollar mold, as apposed to what lyman/rcbs are going for these days.

Ain't that the truth.

Don

Mihec makes a hell of a mold, but I foolishly ordered a 4 cavity, which is way too heavy. I sold it. I picked up a comparable mold from NOE, and it is beautiful too. My last one from Accurate was also brass, and like the others, it is amazing. I may try an iron mold from Accurate next, but for me I'm not sure if the cost is worth it.

While I like my Mihec molds and marvel at his machining, brass is my least favorite material for a mold as I find it is the goldilocks material in terms of having the narrowest range of not too hot and not too cold to cast good bullets.

And yes, I have a couple of the 4 cavity molds and they are heavy mo-fo's. I would much rather they were made from meehanite and I likely wouldn't have sold my 476640, but as it was I simply couldn't get the right temp where I was hot enough to get the noses would fill out or too hot so the base would be damaged when I dropped the bullets from the mold.

I've purchased an NOE brass 2 cavity for my 9.3, my first foray into casting. It seems to take forever to heat up but then it's great.

The only issue I've had is small bits of alloy sticking, which prevents the mold from fully closing, causing flashing and bad bullets. Then I have to heat the mold to the point I can wipe the lead bits off. Anyone else have this problem?

Accuracy with my mild loads has been great, experimentation with full velocity powder coat continues. If I could figure out this sticky business all would be well.

Brass molds are susceptible to tinning, where the lead alloy adheres the to the blocks just like solder.

The key is to heat cycle the mold a few times before casting to allow the surface of the mold to oxidize which should protect it from tinning.



Something I haven't always understood or appreciated as shown by the lower mold.

Do you mean just heating it in the oven? I can certainly do that a few more times. How do you like to remove the tinning?

The gentlest way to remove the tinning seems to be with a hot mold use a contractors pencil or piece of wood and push it along the surface of the mold and the lead comes off. If the mold is cold you can very carefully scrape it off with a razor blade.

I learned about the heat cycling to form an oxide after I'd used my brass molds enough to build up an oxide layer from casting. I'd imaginge baking the mold in the oven at 500F for an hour or so ought to do the trick.

I use the carpenters pencil for some cleanup as well. Sprue smears on the underside of the plate is about all you should use them for; any more and youve got stuff way too hot.

I dont find the issue exclusive to brass moulds though. Its usually an incident of mould temp AND alloy temp with flow being too high at the same time. Either back off the alloy temp or let the blocks cool a bit. Take care to note both when cutting the sprue. A half cut/smear is about right. A clean smear and base means there's probably too much heat in both the alloy and mould temp..

If alloy flow is too quick, along with the other instances, the mould venting will not keep up and the alloy will flow in those vents, causing fins.
Also note the blocks should also be shut tight and set to cool tight; keep the handle under tension and take care that the pins dont lose full engagement. If its smearing on top of the blocks when cutting sprue, odds are you will have tinning on the faces as well, regardless of block material.

If lead is all over the block faces every trace must be removed or else the same issue will continue.

I dunk my moulds until any top block residue is liquious and then brush top and faces with a fine bronze bristle brush until clean and let sit until the mould is agreeable.
Casting with lead on the mould faces will just make the issue magnify as casting resumes.
With tight pinned, moulds, always be sure the mould is fully closed and be sure when the mould is set down to cool you arent jostling anything loose.

The LEE moulds any shallow pins especially need close attention.

Thanks for the info Hawk. I'm thinking I let the blocks get too hot and the alloy was flowing too fast because the problem started at the bottom of the pour.

Make my pistol / lever gun molds all aluminum especially when casting with harder lead alloys. I like the lighter weight of the molds. Bottom pour or ladle casting doesn't matter. Keep the sprue plate lubed to prevent galling and the molds should last forever. For the larger long range black powder cartridges with 30-1 / 20-1 alloy I still prefer iron/meehanite molds because of the higher melt temp required to cast match grade bullets. Tried brass molds and never really cared for it at the time.

I've never run into any tinning problems with my brass molds. Just ordered another one. I got a 2 cavity mold a couple of months ago that makes a bullet that is so versatile that I can use it for both .45 ACP and .45 Colt. So, I just had to get the last 4 cavity mold that Mihec had for this bullet.

Don

Not very experienced here, but when my Lee molds shearing starts to have a smear, I just slow down my cycle. Let it cool just a hair between fills. Works for me. miles

Do you fellows always cast with one mold or more?

I always use two in rotation, while one is cooling and the sprue hardening I'm filling the other one. That generally seems to keep the mold temp from getting too hot but even with that if you have two six cavity aluminum molds for large bullets, say a .45 and a .44, you occasionally have to let them cool down a bit.

I always just use one, as I'm casting hollowpoints and you need to keep the hollowpoint pin hot.

Don

I just cast with one usually, because swapping molds slows me down. I tend to cast quickly though, and quench the mold every 5-10 casts to keep it cool enough.

I usually always cast with two, sometimes 3 of the same material, block size and nominal bullet size.

A hotplate can be used if needed for a mould out of geat sequence.

Really small bullets/moulds like aluminum 22s may need solo attention, but the hotplate can allow even them maintain a consistent cycle to empty the potm