brass VS aluminum molds

[HVACscott]

How do these 2 mold materials differ as far as casting?
which lasts longer if either
why would i buy one or the other?

[Winger Ed.]

They both work.

My only issue with Aluminum molds is they tend to get sloppy and wear out sooner if you're a little rough with one.
I sometimes have trouble keeping the heat right with them since the Alum. cools so much faster than Iron or Brass.

Until I dinged them up, a Lee .357 DEWC and a 200 .45ACP molds made boolits
that were among the most accurate ones I've ever cast.

But they didn't live even close to how long my Iron ones have.

[HVACscott]

thanks good info

[Bazoo]

I prefer iron moulds. Aluminum moulds cast fine when you're going fast but if you stop to flux boom, the temperature drops. An iron mould holds that heat just long enough. It's not just that, iron casts easier to me.

That said I've had an accurate in aluminum and it was a joy to cast with. So are my RCBS moulds. Then at the better then nothing level is lee. They work most of the time, they are ornery and often don't drop the bullet easy. If you're handy and dont mind tinkering, they are a good value.

[farmbif]

brass mold holds heat. I really enjoy casting with mp brass molds, but have a noe 4 cavity aluminum that casts perfect bullets every session. and one of my favorite iron molds is an old ideal 358156 that also makes perfect bullets every time. they all work. for what lee molds cost they are well worth the money.

[Winger Ed.]

If you go with Lee, I'd encourage getting the 6 hole variety.

They're good, and if you're careful with it-
you can probably cast several hundred pounds of boolits with one until it gets a little sloppy or the handles break.

[wv109323]

Both have their own personalities. Brass is heavier but not unreasonable if 4 or less cavities. Brass seems to be more tolerant with mold temperature. I seem to get a place in the mold where the lead sticks to the mold which makes bullet release more difficult. Aluminum molds seem to get hot spots in the lube grooves and require a more regulated casting speed. Both can produce excellent boolits.

[kungfustyle]

Cast in winter, that's all I'm saying. All kidding aside, if you cast outside below 60, you will put your aluminum molds up for the season. Brass and iron will hold heat well enough for a good casting session under those conditions. Aluminum works great all year if you can control the temp in the room you are casting in.

[StuBach]

From my experience:

iron will last longest, take the most abuse, holds heat best and drops easiest. I have numerous H&G and Ideal iron molds (single cav all the way up to 6 cav) that have lasted since the 40s when Grandpa bought them. Highest recommendation if you can find/afford. To my knowledge only maker still doing iron is Accurate and his molds are pricy but I’ve heard good things.

Brass molds work great. Don’t hold heat as well as iron but pretty nicely. Use a hot plate to maintain temp and you’ll be golden. Speed is also your friend with brass, the faster you go the easier bullets will drop. Added benefit, you can get brass molds with HP/HB pins if desired. Drawback, make sure you season mold prior to use otherwise they’re a pain till they break in. Also, they are not very durable against abuse so treat them tenderly and they’ll last.

Custom maker aluminum (MP/NOE/Accurate) molds are high quality and have the benefit of usually being the lowest cost option offered from that manufacturer with great value. Benefit is the heat up quick if using a hot plate (recommended with all materials) or you can just dip a corner in the lead for a couple seconds to heat the mold up. Also have the benefit of being offered with HP/HB pins at NOE. Drawbacks: won’t stand up to much abuse since aluminum is so soft, tend to overheat so keep a wet towel around so you can set them down to cool if needed.

Additional drawback to MP/NOE brass and aluminum, if the mold is not in stock than you have to wait for the next group buy to get the design you want. Accurate makes to order so you usually just have a few week lead time.

“Value” aluminum (Lee) molds are a great introductory mold for those just getting started and needing low cost options. Benefit is they allow you to try many designs if you want with not much cost (comparably to custom makers). Drawback, often times the cavities are not 100% uniform or consistent in dimension one cavity to another in the same mold. Uniformity can be somewhat resolved by “beageling” (search forum for it) but unless your a machinist your not likely to help the inconsistent cavities much. Added perk, their always available online and reasonable cost.

Bottom line, all molds can be mastered and used depending on your patience. Buy the best you can afford and enjoy. All molds can be made to work and there’s a lot of guys on here that swear by the “cheap” Lee’s and will never use anything else and they work great for them. Others prefer the classic iron molds and scour thrift stores and eBay for the venerable classic HG molds. While others prefer the newest hottest custom group buy on here and have no problem sometimes waiting months or years for a GB to finish.

Best advise, find a local caster and try as many as you can, see what works for you and buy that.

[Tripplebeards]

The only thing I don’t like with brass molds is I get tinning every time I use it. I have seasoned my mold by heating it in the oven a dozen times plus in a row by placing it in my oven and it doesn’t matter. I cast really hot so tinning will always be a on my future. Takes an afternoon to clean off and reassemble. I have found no easy and fast way to clean it off. The only way I have been able to clean my tinning off is lightly heating with a butane torch and scrubbing the tinning off with a brass or bronze barrel brush...pain in the but. I don’t get tinning with aluminum or iron molds. My cheap Lee aluminum molds are the fastest and easiest to cast with IMO. They do loosen up with hard use as stated. I had a .358 200 grain lee mold loose as a goose before I ended my first casting session with it. The good part is the 2 place molds are only $25 to replace.

[Bazoo]

The best luck Ive had with lee moulds is buying used. I guess someone has already taken the time to beagle them, or just used them enough to break them in. I have 3 used lee moulds that all cast great. I have several newer ones that all are frustrating. After all the time I spent tinkering on them, I regret having went that route. But I'm a sucker for a deal so, I keep going back for more, hoping for another keeper.

[trebleplink]

I'm a newbie, using Lee 6-cavity molds. The issues I've had are: 1. Sprue plate leaks, so often have flash on the bases. 2. I've got to really clamp it closed with good force to prevent flash between the two halves.

[country gent]

I prefer brass over aluminum then steel as mould materials go. Brass seems to heat more evenly and hold it better. I have 5 old west brass moulds by Bernie Rowels and they are great moulds. Handled like a precision tool should they last forever. My cast iron / steel moulds are all rcbs lyman and Brooks they cast very well and hold heat well but they dont seem to hold heat as well and seem prone to hit spots.

Im hoping here shortly to cut my first mould for bullets A 45 caliber at around 525 grns. The blocks will be brass a 1/4" thick vented sprue plate, and rcbs style handle mounts 2 cavity nose pour. My reasons for brass are 1) it machines easily and produces great finish easily. 2) Dosent Gaul to cutters like aluminum. 3) If I need to I can cut the cherry from 4140 pre hard and use as is. 4) cutting brass produces a manageable chip.

Using aluminum gauling may become a problem and finish isnt as easy to get. I could use the pre hard but aluminum is more abrasive than brass. Steel / cast iron is harder and would require grinding the cherry from an old end mill slower feeds and speeds and possibly hand lapping to get the best Finnish. Both of these materials may require some stress relieving to get best results. Steel isnt to bad but finding cast iron in the size required easily is an issue.

You buy what you can afford or save up for what you want. I have used Lee moulds with good results and they are a fine mould. Not as durable with rough handling. I havent used the "upper end" aluminum moulds yet, but hope to. My Iron moulds are easy to use but do to the harder machining and slower cutting times and added hand work cost may be more.

Several things Im planning on adjusting is the sides of the lube grooves will be 10-15* on a side to aid release the corners will be radiused instead of sharp corners. Instead of the normal .812 ish spacing Im going to go 1" for a little more mass between the cavities. I may make 2 cherries 1 rougher that leaves .020 and a finish to cut to size in a second pass. Vent lines will be cut with a 4" fly cutter and 60* vee tool .003 deep on a side at a .150 spacing, 3 alignment pins with pre hard bushing in the brass.

Ive also wondered about best of both aluminum blocks with steel insert where the cavities are

[HVACscott]

thanks for all the good info

[trebleplink]

What's a cherrie? None of my machinist friends have heard of it. Some kind of cutter I presume?

[country gent]

A cherry is a cutter made to cut the bullets form. Basically you cut the bullet in a stem flute and harden then sharpen. It is set centered in a double acting vise ( both jaws move). the mill is started and the jaws with the blocks in them are closed on the cutter cutting the cavities. AN air hose is also blowing in the gap to remove chips and any binding they may cause.

[trebleplink]

I see. I wondered how they were cut. I guess there is rod stock in the alignment holes. I wondered: maybe some kind of micro boring bar ...

[ulav8r]

Some modern molds are made using a boring bar in/on a cnc lathe. Allows easy change of design or individual features of a given design, such as changing diameter of grease grooves, width of groove/bands, bullet length, nose diameter, taper, etc.

[Burnt Fingers]

I separate out aluminum molds into three categories.

1. Two cavity Lee
2. Six cavity Lee
3. Everyone else

I have aluminum molds from NOE, MP, and Arsenal. Those are great molds. Inexpensive, high quality, and hold heat well. The more cavities the better the heat retention. Awesome for six and eight cavity molds.

Lee six cavity molds. Limited selection, they work, they are very inexpensive, and hold heat for a short time.

Lee two cavity molds. Better than nothing.

Brass....Brass molds are awesome. They hold heat better than any other metal used. They like to be run hot, you can run them faster than a iron mold in my experience. However they are heavy and do cost more than quality aluminum molds.

Iron....Lighter than brass, holds heat almost as well, the most expensive material used, can rust if not handled correctly.