Brass mold temperature question

[Dolomite_supafly]

I have looked an can't seem to find an answer.

I got a 3 cavity brass Accurate mold and it looks great. It is using a bullet I designed for my 300 Blackout. I have tried every subsonic cast bullet "designed" for the Blackout and every single one of them sucks. I was pretty disgusted with the cast bullet designs currently out there for the 300. On every single mold out there you have to load them to magazine length which can affect reliability in a standard magazine. When you seat the bullets deeper, for reliability reasons, you expose the lube groove to the powder.

The "new" design is 240E in Accurate's catalog and actually comes in at 244 grains using wheel weight lead. I removed the bottom lube groove to allow the bullet to be seated to 2.10" without exposing the lube groove to the powder.

So on to my question. I cleaned the mold using Dawn dishwashing soap and a very soft tooth brush before use. I let it dry overnight then began casting this morning. This is my first brass mold and I have always used aluminum molds in the past with great success.

But it seems like the brass mold is either harder to warm up or needing more heat to cast bullets. I set my pot at the same temperature I do for my Lee aluminum molds. I am using a Lee production pot and I set it at 4.5-5. I pour the mold then set it down for about 20-30 seconds. Knock the sprue off then drop the bullets out. I cast about 50 bullets and the mold was still throwing wrinkled bullets. I stopped what I was doing and allowed the mold to cool for a couple of hours. I cleaned it again to make sure a contaminate wasn't causing the problem. And again it was casting wrinkled bullets. Other than the wrinkles they are nice and shiny and dimensionally identical. I tried casting bare as well as with the mold sooted up and could not see a difference other than the sooted mold didn't have bullets as shiny as the bare mold. The bullets are not sticking either when clean or when sooted.


Is the mold not hot enough?

Is the lead not hot enough?

What temperature should the mold be for lead wheel weight lead?

I am going to pick up a thermometer so I can measure the mold's temperature. Also, is there a temperature I want to stay below to prevent warping?

Thanks
Dolomite

[Jailer]

Are you pre heating your mold? You will have best luck pre heating your mold on a hot plate before you start casting.

You'll likely have to turn the heat up a bit to get consistently good bullets. Brass molds like to be run HOT to work well. A thermometer will go a long way in helping keep things consistent. I have to run my melt at around 720 or so and cast FAST to keep my brass molds up to temp. Cast fast and adjust your sprue puddle size to help regulate how much heat you are putting into the mold.

You're right about them being heavy. I prefer aluminum molds just for that reason alone.

Good luck!

[Dolomite_supafly]

Ok, that is what I was thinking. I know with aluminum molds I get the same krinkled look before they get to temp.

Thanks

[runfiverun]

run the mold a couple of times before doing a big run.
just heat cycle it to hot and back to cold.
this will oxidize the mold and the cavity's making it easier to run

[mrbill2]

From Accurate Molds website: "Brass molds can warp if overheated. This will not happen with normal casting temperatures, where the mold block typically reaches about 325 degrees. If you preheat your molds, be careful not to get brass too hot. Brass makes a great mold block, but cannot be abused. I do not guarantee against warpage."

[blikseme300]

I don't seat to magazine length and I have not had any problems with feeding. The boolits I use are from 3 molds, Lee 312-155-2R, RD 165 & RD 170gn. Seating depth is determined by where the GC is located in the case and not by the magazine. I don't lube all the groves in the RD boolits so no lube is exposed.

I saw your mold on the other forum and am interested in how it performs. I don't care about staying subsonic but anything cast in 300blk interests me.

Bliksem
Sent from my iPad using Tapatalk

[MBuechle]

I've got three of Miha's brass molds. They need to be run just under frosty boolit temp. I pre heat on a hot plate and if interrupted set on hot plate to keep warm. If I have drive band fill out issues, I'll set mold on hotplate sprue cutter down. My sprues take 4-6 seconds to harden frosty and can be cut by hand when things are going right. I don't run my alloy any hotter than I do for aluminum molds, no thermometer so I don't know what that is.

[HATCH]

I run it at 800 degrees.
Just adjust your casting speed to keep the mild warm.

sent from my mobile.

[HARRYMPOPE]

I run my brass Eagan's hot like HATCH does also and adjust speed to match.

Wait.....that's what i do with all of my molds<G>

Funny thing is my 22 Eagan's get to temp as fast as my 30's.This is without pre-heating.


g-

[MT Chambers]

I preheat all my brass and steel (iron) molds as you can cast along time before you get a "keeper" without the preheat.

[40Super]

My Accurate molds and M-P's are run conciderably hotter than any of my other molds. I usually pre heat quite a bit higher and turn the pot temp up about 50*F warmer than usual and cast as fast as I can till I start getting frosted bullets. Then I turn the pot temp back down and slowly adjust my speed down till I am just so not getting frosted boolits anymore. Then I stay there, that is usually in the heart of its sweet spot. With some HP molds, that sweet spot is very small.

[Dolomite_supafly]

I got it all sorted out. I had the mold too cold and the lead probably was too. I upped the temperature to the upper 700's until the mold started casting wrinkle free bullets then I turned the lead down to the mid 600's. Then I went crazy and cast a few hundred last night. All turned out great.

I think another problem was I was using pure lead when I am used to using WW lead. I had a friend send me a bunch of lead cast in 12 gauge slugs. I didn't realize they were pure lead until I talked to him. I was trying to cast the pure lead like I do WW lead.

Thanks for all the advice guys. This is my first brass mold so I have a little bit of a learning curve.

Dolomite

[40Super]

Your probably not going to want pure lead for boolits in that rifle. Did you alloy it with some antimony and tin after finding out it was pure?

[Jailer]

I got it all sorted out. I had the mold too cold and the lead probably was too. I upped the temperature to the upper 700's until the mold started casting wrinkle free bullets then I turned the lead down to the mid 600's. Then I went crazy and cast a few hundred last night. All turned out great.

I think another problem was I was using pure lead when I am used to using WW lead. I had a friend send me a bunch of lead cast in 12 gauge slugs. I didn't realize they were pure lead until I talked to him. I was trying to cast the pure lead like I do WW lead.

Thanks for all the advice guys. This is my first brass mold so I have a little bit of a learning curve.

Dolomite

The reason you had trouble with pure lead is that it has a higher melting point than WW alloy. It takes a higher temp to get it to fill out before starting to solidify in the molds as well. You have to raise the melt temp to cast pure lead if you want to get decent fill out. The good thing about it is you don't have to worry about frosty boolits.

[tbj555]

I find the same thing pure lead takes more heat to fill out.