HELP! ......I'm having problems with a Mihec brass mold!

I have a Mihec brass four cavity mold for the .455 Webley Hollow Base Boolit, and I have been having a devil of a time producing good boolits with this mold!

As you can see in the picture, I am having problems with ?fill-out?.

If I get both the mold and the lead REALLY hot (?.too hot, in my opinion) I might get 25% of the boolits to fill out completely: ??But if I work the mold fast enough to keep it that hot, the boolit skirts crack due to the opening stresses!

If my math is correct, the alloy I am using contains between 3% and 4% tin, and it is quite soft. (?Easily marked with a fingernail.)

I cast maybe 1000 boolits a month in other calibers, and I have never had issues like this: ??..Can anyone shed some light on this problem?

Do you think more tin might be the answer???

Kent

Boolit Buddy Join DateJan 2013Posts60

might a venting issue several stickys on the subj

Boolit Mold Join DateMar 2013LocationW. Central INPosts18

venting or mold fouled with oil.
I'd start by making positive the mold is clean..maybe boil in a TSP solution.

you may be opening the mold before the srue is hard enough
causing the cracked or torn skirts on the hb
never had a problem with any of Mp's molds
I think after you cast awhile with it things will work out

Wash the mold with TSP. It'll be squeaky clean.

TriSodium Phosphate

I used the powdered form and I bought it in home depot.

Rich or poor, it's good to have money.

Well klcarroll, the first thing you should have done is contact the mold maker (MiHec) and throughly describe your problem along with your "procedure" for using the mold. Since he sold the mold he has an obligation to make sure you are using it correctly.
It could be a bad mold or it could be you. However it appears you do have experience in using bullet molds.

Then post back if there is a problem with him using his instructions or whatever.

Well klcarroll, the first thing you should have done is contact the mold maker (MiHec) and throughly describe your problem along with your "procedure" for using the mold. Since he sold the mold he has an obligation to make sure you are using it correctly.
It could be a bad mold or it could be you. However it appears you do have experience in using bullet molds.

Then post back if there is a problem with him using his instructions or whatever.

Sorry! ......I didn't realize I was violating established protocol and procedure!

Please forgive my ignorance!

KLC

The picture of the bullet you posted does not appear to be frosted indicating a hot alloy and mould. How loose is the sprue plate? If it is too tight it will prevent air from escaping causing defects. As other have already said try cleaning the mould again.

I have had problems with fillout in the past and when I have exhausted all other methods to correct it, i.e., cleaning, venting, sprue issues, I turn to lapping. I quick five minute lap with 500 grit lapping compound using two or three boolits cast from that mold and that cavity usually works. I believe the problem is a cleaning issue that ordinary scrubbing with detergent can't cure.

Paul G.
Once I was young, now I am old and in between went by way to fast.

The end move in politics is always to pick up a gun.
-- R. Buckminster Fuller

It appears from the picture the melt temp is less than 700F and mold temp nearly half that. Also looks like the mold has some impurities in the grooves facing us. I would scrub the mold with a soft toothbrush and diluted solution of scratch-free Comet (AKA liquid Comet). Then I would warm the mold on an electric hot plate up to about 450-500F and introduce 725-750F metal into it. If the sprue stays liquid for about 3-5 seconds, you should be in the zone. Don't open the mold until the sprue looses its shine. Also, lube the sprue plate with Bullplate or an equivalent.

MJ

P.S. Also, scrub the mold face parallel to the vent lines and make sure there are no burrs impeding the venting.

It's not about gun control, it's about people control. The progressives are using terrorists and the insane to further their agenda. If the socialist news media wasn't complicit, we could sit back and watch Fast & Furious and Benghazi-gate unfold.

Thank you all!

I will try the actions that you have suggested.

KLC

MP molds, especially the HP and HB cramer types, need to run very hot. Until I got a hotplate, I couldn't get a Miha crammer type HP mold to work until it was very hot. By pouring a lot of boolits real quick, it finally got hot enough.

Forget about worries oh, I'm gonna warp it if I get it too hot! I don't have an exact heat number to list, I just turn the hot plate on high, leave the mold on there for 20 minutes. it STILL is not hot enough! The HB pins need to be hot enough so they don't suck the heat out of the metal before it can finish filling out. Since it is a nose pour boolit, you have to run the lead in there as fast as you can, no dribbling.

My big 500 S&W "grand canyon" 700 grainer actually only works when I use a ladle. I'm using a pretty soft alloy so I can expect some expansion of the enormous HP cavity boolits. It still has to be very hot to work.

Don't try to solve the heat problem by cranking the alloy heat up. That depletes the tin which makes fill-out worse. Get the mold hot, leave the alloy at about 725-50.

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You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart.
You owe it to him to be worthy of such devotion."

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Since it is a nose pour boolit, you have to run the lead in there as fast as you can, no dribbling.That's a good point too. Perhaps you need a Rowell ladle. The #2 is my go to ladle for .30 caliber and bigger molds... it really keeps the blocks operating at a consistent temperature.

MJ

It's not about gun control, it's about people control. The progressives are using terrorists and the insane to further their agenda. If the socialist news media wasn't complicit, we could sit back and watch Fast & Furious and Benghazi-gate unfold.

When i cast with my mihec molds i run it at 750
the longer the mold runs the better the boolits will get until it starts to frost.
If i am on a roll i sometimes crank the heat up to 775
If you have the mold at correct temp the sprue cuts with no effort.

You did nothing wrong with posting your question here like you did.
If you want a answer right now then go to the chat room. Someone there will know the answer to most casting/mold issues you got.

I would also run it at about 725. All my hollow points Mihecs like that temp. I also like frosty bollits. It tells me they are hot enough. I turn on the music and really fly when I get my molds up to temp. I never stop to check on the boolits. I don't put the sprues back in the pot until it is time to take a break or run out of alloy and need to refill.

I'm with all the "run it hot" comments. Cast fast and keep the mould temperature up. If that doesn't do it and skirts are tearing then I would suspect venting.

It certainly wouldn't hurt to scrub clean though I seldom ever clean new moulds other than wiping down well with a paper towel or rag. What I do is pre-heat until they smoke. You do not want to overheat and I do not have any temperatures to give you but I have heated until the sprue plate lube starts to smoke and that is probably just a bit too hot as the sprue takes a while to harden when I first start casting. I set my casting rhythm and lead temperature from there and stay casting quickly. I have not warped a mould yet.

All my brass moulds (and NOE aluminum) like to be run fast and hot.

Another thing I have had to do with some moulds is to use a fine stone or diamond hone to just break the top edge of both mould faces under the sprue plate. That adds a bit of venting. Usually rounded bases (in your case nose) or at least fill near the end of pour is not good if the sprue plate is tight and venting under is poor. Simply loosening the sprue plate may help.

I would check out all other options before lapping a Mihec mould.

Longbow

I have had problems with fillout in the past and when I have exhausted all other methods to correct it, i.e., cleaning, venting, sprue issues, I turn to lapping. I quick five minute lap with 500 grit lapping compound using two or three boolits cast from that mold and that cavity usually works. I believe the problem is a cleaning issue that ordinary scrubbing with detergent can't cure.I would be really hesitant to lap a MP mold until I had tried a whole bunch of other options first. My first suggestion with almost any problem with the MP brass molds is that they need more heat. More heat (in the block, not necessarily the melt) usually solves the problem.

NRA Endowment Member

I don't own an assault weapon. I own a counter-assault weapon.

You paid top dollar for the mold. You shouldn't need to modify it in any way.
Clean it with brake cleaner.
Start casting hot
If in 30 mins you don't have good boolits its got a issue

I have a 375449 mold that makes the best one sided boolits in the world.
flip them around however and they get all rounded over like you have in that picture.
mind you this is a 2 cavity lyman 375 caliber mold and I should be looking for way's to cool this mold down.
but no sir I have to run it hot and fast like 5 pours a minute and waterdrop.
I have cleaned the vent lines and recut them.
the sprue plate spins in a light breeze.
I have polished the cavity's.
and after all that.
I have to run it smoking hot and fast, the boolits pop out of the cavity's and are well filled out, anything else is a waste of time.

it's all an educated guess,,,, till the trigger is pulled.

the more i find out about shootin boolits, the more it contradicts everything i ever learned about shooting jaxketed.

Sorry! ......I didn't realize I was violating established protocol and procedure!

Please forgive my ignorance!

KLC

Hi klcarroll, I am certainly not implying you are ignorant ! You spent your money for a tool that is giving you a problem. It's very reasonable that you contact the manufacture before jumping to conclusions.

Who else would be better to help you than the person who made the tool? I can understand your frustation, However, there is a way to begin such problems other than "shooting" the messenger.

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