Casting aluminum bullet molds

[Texandy]

Ok, forgive me for I am new here and to this hobby. I've reloaded but never cast my own bullets.

One of my other hobbies is CNC. Mostly woodworking. Various gun grips and such.

But I've been itching to try my hand at pouring aluminum. How well do you think a lost-wax casting would do for aluminum bullet molds?

I realize there would be alot of trial and error involved to account for shrinkage of the mold as it cooled. But would you get a high enough resolution at normal atmospheric pressure to wind up with a mold that was suitable for lead bullet casting?

[Chamfered]

Pouring aluminum is something I have looked into also but not got around to. As far as casting molds goes, I don't think any of the mold companies manufacture them that way. I know sand casting molds can only get within .030" for one horse motor sized endbells, from previous tech work that I used to do for a living. If your into CNC I would go the route of trying to cut my on cherry for mold making.
Good Luck

[Texandy]

I haven't cut much metal with my mill. Only a bit of aluminum in very shallow cuts. It's really just for woodworking.

But, that does make me think that it might be possible to do a casting and then finish it on the CNC.

[220swiftfn]

You can try it, it might even work. BUT.... I wouldn't get your hopes up too much, I'd be willing to bet that you're going to get a lot of casting voids and pits in there..... whether or not they'll be a problem when you cut the face and cavity????? (That's why forged stock is better, but you might get lucky.)


Dan

[closebutnocigar]

We did it about ten years ago.

In my shooting club there was an retired ingeneur from Alcan Aluminium; they produce Alu and manufacture things.

We used iron moulds (lyman) and he had a special kind of mould prep.

We lost about 3 of 10 bullets and it took a lot of time to wait for the mould to cool down.

Then he gave a special lube because alu oxide is very hard and kills your barrel.

Afterall the problems just started: When shooting (45-70) the bullet began to burn !!!

We couldn´t believe it, but that´s the way it was.

[Salmon-boy]

I started casting Aluminum as a hobby about 15 yrs ago. So far I've made a whole bunch of ingots and two actual parts -- Mostly because my woodshop has been in storage..<sigh>

Casting the actual boolit moulds with cavities in place is not all that easy. Aluminum shrinkage would make holding the tolerance of .001 almost impossible. What you might be able to do is cast your own mould blocks with pre-located pins and pilot holes for the cavities.

For a good short read, try out the Gingery Charcoal furnace and Metal Shop from Scratch series.. That's what got me hooked.

[Elkins45]

If you look on the main page of this forum you'll see a thread titled "worlds worst bullet mold" or something like that. The mold referenced in the thread is a mold made by a maker that is best known for making sinker molds. It looks like it may have been cast....but commenters haven't been very kind in their remarks about it.

[geargnasher]

The problem is making a two-piece mould that lines up.

Gear

[Texandy]

I started casting Aluminum as a hobby about 15 yrs ago. So far I've made a whole bunch of ingots and two actual parts -- Mostly because my woodshop has been in storage..<sigh>

Casting the actual boolit moulds with cavities in place is not all that easy. Aluminum shrinkage would make holding the tolerance of .001 almost impossible. What you might be able to do is cast your own mould blocks with pre-located pins and pilot holes for the cavities.

For a good short read, try out the Gingery Charcoal furnace and Metal Shop from Scratch series.. That's what got me hooked.

I have the first two books in that series. My foundry is mostly finished. Still need to make a crucible, a lid, and tongs. It's a great read, for sure.

Gingery's lil' bertha furnace is on my list of stuff to make, partly because of how convenient it would be for doing large lead melts.

[Texandy]

The problem is making a two-piece mould that lines up.

Gear

True. Unless it was cast as a single piece and then had pins and holes drilled while it was a single piece.

But then you have to account for the kerf of whatever blade you use to split them.

I can see a possibility where you could cast it as a single piece intentionally too thick with all the cavities as ovals, then drill your locating holes, then split it on a bandsaw. Then run a fly-cutter over each piece to true both mating surfaces and reduce thickness until the cavities are all round again.

The more I consider this idea, the more I think it might be easier just to build a beefier CNC and cut aluminum barstock...

[500MAG]

You have never cast your own boolits and are wanting to make a mold? Is this what they mean by "cart before the horse"?

[Texandy]

You have never cast your own boolits and are wanting to make a mold? Is this what they mean by "cart before the horse"?

A horse-pushed cart you say? What a fantastic idea!



Honestly, I don't see them as mutually exclusive propositions. I've got an order in on the NOE group buy thread for 247 gr for my 300 blk.

While I'm waiting on that, I'll probably get a 2 or 3 cavity lee mold for my pietta 1860 reproduction.

But nothing says I can't play around with making chips at the same time...

[paul h]

I think it would be exremely difficult to get the kind of accuracy you are after in a bullet mold, to withing 0.001" with a cast mold.

All the precision cast parts I'm familiar with still have their critical surfaces machined.

To my way of thinking if you cast a mold and machined the critical surfaces, you'd have just as much time in putting the parts in fictures and machining than you would starting with aluminum billet.

[delt167502]

I worked in a Die cast foundry.The boss decided to sand cast but found to get a good solid fill the aluminum needed to be under pressure.

[.22-10-45]

Hello, Texandy. Back in the 90's, Wolfe publishing brought out a couple of cast bullet handbooks..now discontinued. I think there is an article in one of them on this very thing.
Back in high school, I needed a .22 heeled bullet for a rimfire reloading project. I copied the Lyman single cavity block dimensions in aluminum. drilled & reamed locating pins, etc.
Drilled small pilot hole (1/2 hole in each block face). Next I turned up a tool-steel "bullet" with dimensions oversize for lead shrinkage. This was hardened 60 RC & polished to mirror finish.
"bullet" placed between blocks, & 50 ton hyd. press used to bring blocks together. The result was a very nicely finished cavity. I made both round nose & flat nose styles.