Beautiful mold, terrible boolits

[curioushooter]

So I broke out the MiHec 359 Hammer hollow point mold I recently received from the group buy. Gorgeous mold. Should be mounted and displayed. It is the first brass mold I have ever used.

Like all my molds I blast it with brake cleaner when new. It came with a little bottle of what I believe is 2-stroke oil, so I applied it as directed to the sprue plate, alignment pins, and the little cramer rods. Very, very small amounts.

I fired up a pot of my preferred alloy 91-6-3 (lead-tin-antimony+pinch of magnum shot for the arsenic), fluxed it (tallow and sawdust), and poured two. Mold is still cold so I was expecting them to be wrinkly and they were. I poured about 15 more and the mold was quite hot by this point, and so was the alloy. Still terrible wrinkly bullets with round edges. I figured the alloy must be messed up so I broke out two molds--an iron RCBS 358-158-SWCGC and an Aluminum Lee 358-125-RNFP six-cavity (which was new, and I sprayed with brake cleaner and lubed with the same 2-stroke oil). After the second or third throw I was getting nice boolits from the RCBS, lightly frosting (to me indicates that its nearly too hot). I cast a 60 or so. Then I refilled the pot with the same alloy and started with the Lee and cast about 200. I had to turn the pot temp down a bit because the Lee mold was getting too hot.

So my conclusion is that Brass is some vodoo or there is something on this mold that brakekleen can't remove or there's some mold prep step needed for brass that I am omitting.

What do you think?

[jcren]

Brass likes patina. Heat cycle to build up a nice oxide finish. Also, brass pulles heat fast until it is close to melt temp.
Also, use a graphite pencil on the hp pins, not oil.

[David2011]

The only brass mold I have used was for .36 caliber balls and I cast with straight lead. It was trouble free, probably because it was pure lead so I'm no help with that part but I have used sprue lube a lot.

The sprue plate oil I use came with instructions something like this; no doubt I'm embellishing:

1. Shake the oil, remove the lid and touch a cotton swab to the inside of the lid getting only a very tiny amount of oil on it. Trust me, that's all it takes to lube a hot mold.
2. Cast some boolits to get the mold up to temp.
3. Once the mold is hot, cut the sprue but leave the boolits in place.
4. Rub a tiny amount of oil on top of the mold, the inside of the sprue plate and on the sprue plate hinge screw.

That will keep the oil out of the cavities and should let you open the mold with a gloved hand.

[Gamsek]

Just got the same Hammer and with long and cup pins I haven’t had any problems on 1st casting, but I did this; cleaned it with brake cleaner then washed it with hot water/dawn, then 3x preheating it on a hot plate, letting it cool. Done that with many brass moulds.

Before casting I let it sit on a hot plate (medium setting or just slightly above) for 2o minutes, set my PID on furnace to 750F/400C. When I pour lead it should take at least 2-3 seconds for sprue to freeze, cut, tap tap to help open it, flip upside and two taps on handles hinge bolt and they fell out.

I haven’t applied any oil before casting. Only after few casts I wipe top of mould with bullets still in, bottom of sprue plate with cotton cloth (2”x4” folded twice) which got only 2drops of oil months ago. Remember less oil is more.

if you preheated your mould and with 750F alloy you are still getting wrinkles after few pours, it could be to much oil. Wash it, start again.

Also mine are not all perfect after first casting, but with brass HP moulds everything starts to really work on 3rd casting. Some say machining oils are imbedded into material so it takes few casting or good cleaning for oils to be removed.
Powdercoated with clear

[Wheelguns 1961]

When I preheat my brass molds, it takes twice as much heat to preheat them as an aluminum mold. I think you just need to get used to it. There is an excellent tutorial at mp-molds.com. Looks like Gamsek beat me to it.

[trapper9260]

Did you smoke the mold ? I cast with brass and no problems. beside AL and steel . preheat helps also. When cast from brass you will need to do it with different temps then the AL mold ,the mold will tell you what will work for it. I use 2 cycle oil my self for lube the parts that needs it on the mold and no problems. This is what I found that works for me.

[RED BEAR]

Did i understand you correctly you lubed a cold mold? I don't have this mold but i do have 2 mp molds and they are without a doubt the best molds i own. I believe you are right i think that its 2 cycle oil that comes with them. Being two cycle oil it doesn't burn off quickly. I would clean it with dishwashing liquid and tooth brush. I am not a big fan of break cleaner but thats just me or maybe the brand i bought. I have to agree with using a pencil on the pins i know it says to oil them but give the pencil a try. A also use a cheep hot plate to heat all my molds and usually get good bullets from the start. All the above post have given good advice. Let us know if you get it figured out.

[Harter66]

I lived in the desert where rust isn't even a thing and it took at least 5 heat cycles and 8 casting sessions to get good bullets out of a 462-420 HB mould ......... I was somewhat frustrated after all of the brass mould braggary to have such a hard time getting a decent bullet out of it ........
Be patient with the patina it will eventually show up then you can master the tight rope between too cool pins and over heated shanks with a the sprue too hot or cold ......

[stubert]

My NOE brass mold won't throw good bullets until it is 430 degrees. The mold is a 350 grain, .460 diameter.

[JonB_in_Glencoe]

A new MP brass mold...
I would Heat cycle the mold 3 times.
Then I would wash it with hot water and dish soap and a toothbrush (nothing else).
Then cast with it, don't apply the sprue plate lube to a cold sprue plate, use a Q-tip with one drip on it, and apply to a HOT mold, you should see smoking from the solvents in the oil burning off.
It may take more than a few casting sessions to built up a good patina to get good boolits.
Good luck.

[curioushooter]

Did i understand you correctly you lubed a cold mold?

Do you lube a hot mold?

I only lubed it at all because it literally CAME with the mold. I have used pencil graphite in the past and I will do that from now on.

I must say though that my bullets looked about the same as what is pictured above (except I started with the flat pin). I don't consider such bullets keepers.

I will clean it again and heat cycle it an try again.

Thanks for the advice.

[RedHawk357Mag]

Heat cycling is an excellent course of action. Normally I am very patient in getting the dull brass color going. I couldn't take it anymore and after three cycles. Lead boogers! Oh well, I got some great bullets to mess around with. Thinking this one is going to be pretty cool.

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[Gamsek]

Do you lube a hot mold?

I only lubed it at all because it literally CAME with the mold. I have used pencil graphite in the past and I will do that from now on.

I must say though that my bullets looked about the same as what is pictured above (except I started with the flat pin). I don't consider such bullets keepers.

I will clean it again and heat cycle it an try again.

Thanks for the advice.

I said mine were not perfect-yet, I was “breaking in” three new brass moulds at the same time, first casting...and you said you got “terribly wrinkled bullets” ...Post some of your keepers, I will try to cast a bit later and see how it goes

[Gamsek]

Second casting, getting better....

[Boolseye]

When I preheat my brass molds, it takes twice as much heat to preheat them as an aluminum mold. I think you just need to get used to it. There is an excellent tutorial at mp-molds.com. Looks like Gamsek beat me to it.

This ^^


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[flint45]

All my brass molds don't cast well until I get them very hot. I also second the patina when new Iran them about three heat cycles tell they had a good dull patina then all was good.

[Hogtamer]

Toothbrush, hot water and dawn dishwashing detergent. Get it HOT! I got perfect lyman 525 gr slugs the first time, just needs to be really hot.

[Streetwalker]

I have a Egan single cavity mold for my 8mm 98k that is made of brass. It is, by far, the most beautiful and well made mold that I own or have ever owned. I bought it at the Big Reno Gun Show for 25 dollars some ten years ago or so. I quickly found out why the previous owner was so anxious to get rid of it....that mold was the most frustrating monster that I have worked with and I have had some real lulu's!! After a lot of diligent research and questioning every experienced bullet caster I knew, I finally was finally able to get that mold to work. The mold itself is massive for a single cavity and the hotter that I run it, the better the fill out. I have seen that same thing with NOE multi cavity aluminum molds as well. Having a good patina really helps as well and that comes from a number of heat cycles being repeated. After all that frustration, I now have a mold that I can use without having to pull my hair out.....and I'm bald enough as it is!!

[44Blam]

A new MP brass mold...
I would Heat cycle the mold 3 times.
Then I would wash it with hot water and dish soap and a toothbrush (nothing else).
Then cast with it, don't apply the sprue plate lube to a cold sprue plate, use a Q-tip with one drip on it, and apply to a HOT mold, you should see smoking from the solvents in the oil burning off.
It may take more than a few casting sessions to built up a good patina to get good boolits.
Good luck.

This is what I do and as soon as the mold is hot, it starts dropping good boolits. I like brass best because it gets hot and stays hot. You have to slow down at times to not overheat, but they work well.

[bangerjim]

I cast pretty much everything now in brass molds. You MUST heat-treat/cure them right off the bat. They need to have a rich golden look to them, not bright & brassy like out of the box. I cycle them at least 4 times up and down at first B4 ever trying to cast the 1st time with a new mold. Once they are cured, they work great every time. And brass likes to be HOT HOT. Just takes some re-training to get you goin'! And you WILL get there. Nice thing, lead.....................it REMELTS!

banger