Aluminium vs steel bullet molds.

Jim,

I have AL, steel, and brass molds and they all have their individual characteristics.

The aluminum ones I use are mostly Lee 6 cavity with a couple of 2 cavity mixed in. When I got them I tried to keep somewhat of a record of what alloy temp they liked to run the best at. It depends on which one as to what temp. That said they will dump a pot of great shooting bullets very quick once you get rolling. The key seems to be the rhythm at which you pour. I set a 10"ish clock up with a second hand so I could sort of dial in my cast rate. IT only took one or two sessions to be able to hit it right so that I kept the mold up to temp but not throwing frosted bullets.

The steel ones are similar but they take a bit longer to get up to temp. Once there they hold the heat pretty well from one throw to the next. The ones I have had the biggest issue with were the Lyman Devastator molds which have the pin you have to pull and reinsert every time for the HP. These require you to go a bit faster, or run the alloy hotter, in order to keep up the pin temp. If the pin cools your going to throw a cull every time.

The brass ones I use are MP molds and I have to say they are the best I have bar none. They need to be up to temp like the rest, but once there you simply pour and dump until your pot is empty. They are all set up to throw either HP or solids or both with the Cramer style pins. It only takes one time of using them to fall in love with the end result.

Things I have found with them all, as recommended by several folks, having an alloy thermometer and keeping the alloy within and certain range depending on the cast result. It will depend on just what your pouring as to what the temp needs to be for the best result. For the most part however I usually stay right in the 700 degree range on average with 740 bing the highest I run and 675'ish being the lower end.

With the molds, I clean them all first with hot water and Bon Ami. I heat them up under the hot water first then scrub them out using an old tooth brush, paying close attention to all of the finer points of the casting areas.

When done I also follow up with a rinse and scrub with brake cleaner and another nylon brush. (might ant to test the cleaner on the brush prior to scrubbing as some will melt, don't ask.) Once these have been done I lube the hinge pins, and sprue plate, and am ready for casting.

I use a small hot plate to preheat the molds, with the knob set to halfay between the medium and hot setting. This usually gets the molds up into the 250 - 300'ish degree range. Once I start casting I throw the first 4-5 pours right back into the pot, and then I go for it.

This usually results in good bullets in the pan right from the get go. I will stop after around 10 or so pours and make a quick visual inspection of some and go right back to it if they look good. With the Lee molds it might take several sessions to get all of the oils worked out of the pores of the aluminum, but once there they work fine.

When I get done I will wipe them done good with a rag and q-tip with a dab of Kroil, while they are still warm. The kroil hasn't shown to impair the first cast much if any in any of the molds and will keep any surface rust from forming on any of the metal parts.

Hope this help, and at least some of it is what your asking about.

Brass
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Adding tin is dependent on fillout and the purpose of the bullet. If you want proper expansion for hunting you want some percentage of tin in your alloy. If it's just for plinking and the fillout leaves sharp edges and no voids then you don't need to add tin.

Nose pour is up to you. A lot of benchrest shooters use one. But the vast majority of shooters use base pour.

Bottom pour vs ladle pour is up to you and your mold. Some large molds might need a ladle to get proper fillout. While other molds might need to be pressure poured. I have a ladle but it's only a just on case toll. I use a bottom pour for casting all my bullets.


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Great post 41. I appreciate it I never heard of brass molds.

Couple more questions. I use straight wheel weights, should I add tin to this?

On a gun you wish to use for precision shooting, in my case a 30-06, would you buy a nose pour mold?

Also [and this is not mass production] do you prefer a bottom pour pot or using a ladle off the top?

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Yep, the Mihec brass moulds are great. Never a mistake to add tin, especially to WW's. Don't have a nose pour mould, so can't say. My .30-06 mould casts a 247gr RNFP bullet. Bottom pour definately!

Don

Aluminum molds are lighter and that makes a big difference in larg size gang molds...less wrist fatigue. They also don't rust in storage and are cheaper. But you have to treat them more careful because aluminum is soft. The lee 6-cavity design will crank out the bullets once you get them at the sweet spot for temp.
Steel molds hold heat better and are more dimensionally accurate. But they are expensive and heavy.

I want a brass 358156 in plain base 4-6 cavity next.

I have used Lee aluminum molds in a number different configurations, calibers and such. They have and do serve me well but as mentioned they are softer. A bit more care is needed with them so you don't scar them. That said when you reach that sweet spot the 6 cavity molds will crank out many bullets, quickly. I love molding bullets. It's the most fun a grown guy can have without going to jail......IMHO

"Steel molds hold heat better and are more dimensionally accurate."

An interesting comment from above post. Please explain whey they would be more dimensionally accurate than aluminium. Thanks

I have always had better success with Aluminum molds and I own several double cavity Lee molds and a couple that I've made.
I cast mostly for my Black Powder shoothing and use pure lead.
Wheel weights I'm not sure of as there are several opinions as to their actual composition.

Steel is more thermally stable than aluminum, it will not grow and shrink as much due to temperature changes. That said, if you are casting at a consistent temperature and the molds are producing a properly sized ball there should not be a problem.

Hey again,

Well for the most part I am pouring up revolver bullets, a few pistol bullets, and still haven't gotten to the rifles just yet even though I have close to a half dozen molds for them. I simply been having too much fun playing with the revolvers and different blends of alloy.

I have a Lee 4-20 bottom pour pot, and have a PID controller which I built using the instructions on the Castboolit site. I gotta say it is the cat's meow for keeping your alloy at a particular temp. You set it where you want, give it a half hour and it will keep things within about 10 degrees to the bottom of the pot.

As for nose or bottom pour molds, I really couldn't give an accurate answer on them. I do have one of the NOE nose pours but other than simply pouring a few to see how they look and what size they came out. I really haven't messed with it. Some feel they are more accurate, I figure that if I am pouring a consistent temp alloy into a consistent temp mold, then the bullets should come out pretty darned close as well. Least the ones I have done so far have.

If the mold is throwing plain based bullets I guess I could see where snipping the nose instead of the base might help you out. Even so it will still depend on how well you are pouring and how well the mold is filling out as to how accurate the end result will be. Then you have to know if your lube is right as well as the size.

I know your looking for top accuracy and in the rifles more than the handguns. I simply don't shoot enough through the rifles yet to give an honest answer other than what I know about the revolver bullets. Now some of the ones I use in them are plenty accurate enough for my standards any day.

Steel Horse Rider said:

Steel is more thermally stable than aluminum, it will not grow and shrink as much due to temperature changes. That said, if you are casting at a consistent temperature and the molds are producing a properly sized ball there should not be a problem.

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That WAS true of course in times gone by but, surprisingly, some of the newer Aluminum alloys maintain stability at elevated temps.
I made quite a bit of Aluminum based tooling over the years much to the chargrin of some of the "older guys".
I have Aluminum molds that I've made in .30 Cal, .38 Cal, .44 Cal, .36 Cal and .50 Cal. that are a pleasure to use.
Precision? Except for the Black Powder stuff the bullets are " SIZED and LUBRICATED" anyway.

I prefer steel myself, but brass is neck and neck with steel. The biggest thing I hate about brass is the weight. With a bad wrist they just s**k. Otherwise they love heat. My Miha molds are top notch, as is my Ballsti-cast (H&G #68), which is my favorite. I have several NOE aluminum and I can't honestly complain about them, I can cast far longer with them.
I add 1 to 2% tin to my ww alloy(sometimes 1% antimony also for 9mm/to WD harden). Most of my casting casting is done at 700F-720F , some molds once the boolits are dropping good I turn the temp down to 675F"ish to keep heat in check.

As for dimensional stability, most of the newer companies make the molds to drop at size when at casting temp, so they are all pretty equal. Lee's can be problematic though.