Lee 6 cavity with fins on the bottoms

[Ruckmanite]

Hi all, I have 2 Lee 6 cavity molds that I cannot get to have clean bottoms. I took them both apart, degreased and cleaned thoroughly, and lightly sanded bottom of sprue plate as well as top of mold to remove lead deposits and gauling. Any help is appreciated.

Thanks Jeff

[MT Chambers]

If this happened to me the first thing that I would try is applying Bullplate lube to the top of mold.

[sawzall]

Make sure the bolts that hold the sprue plate on and the one on the other end that holds the plate down when closed are tight and the wave washers are present as is the little "forcing cone". Also if you are pressure pouring, with the spout of the pot or ladle right against the holes in the plates it can have enough pressure to push out the top of the mold and give fins as well.

[Casting_40S&W]

Definitely galling under the sprue pivot. Takes about .010" of clearance to flash/fin..

[Ruckmanite]

Definitely galling under the sprue pivot. Takes about .010" of clearance to flash/fin..

Well I took it out and sanded there....

[Ruckmanite]

If this happened to me the first thing that I would try is applying Bullplate lube to the top of mold.

What is bull plate lube?

[Casting_40S&W]

Are you pressure casting?

[Ruckmanite]

I use a bottom pour pot, not sure what pressure casting means, sorry

[VHoward]

Pressure casting is when you hold the sprue plate hole you pour through up against the spout ot the pot and then dispense lead. The pressure of the lead in the pot is supposed to help fill all of the cavity. It works, but there is a learning curve to get it right.

Bullplate lube is basically just synthetic 2 stroke oil. I have used both and both look and feel and act the same to me.

[Ruckmanite]

No, I'm definitely not pressure casting. I mean, my mold rests on the bracket under the spout on my bottom pour, and its about 2 inches from the spout.

So I need to put some synthetic 2 stroke oil on the sprue plate and top of the mold, then take it apart again and sand around the sprue plate pivot and retest?

[Larry Gibson]

Don't hold the sprue handle when pouring. Only hold the mould handles. Doing that cams the bottom of the blocks slightly open. With the bottom of the blocks slightly open the top of the blocks aren't level with each other which causes gaulling when the sprue plate is opened.

Larry Gibson

[Ruckmanite]

Don't hold the sprue handle when pouring. Only hold the mould handles. Doing that cams the bottom of the blocks slightly open. With the bottom of the blocks slightly open the top of the blocks aren't level with each other which causes gaulling when the sprue plate is opened.

Larry Gibson

Ye, I never touch the sprue plate handle while pouring, thanks though.

[country gent]

Check alighnment of the tops of the blocks at parting line to make sure they are mating up properly. ( a smooth junction with no feel to the joint), This will cause fins on half the bullet. A to loose sprue plate can also allow finning to happen. Another is bent or warped sprue plate. What temp and alloy are yopu casting at or with? High temps can cause lead to flow imto areas with smaller gaps. Tin also improves flow a high tin alloy at higher temps may be causing the fins also. Your alloy can have a big affect on bullets fill out and looks. Temp is the same. some where around 700* should be the sweet spot for most moulds alloys. Mold temps can also have an affect on fill out finning. A very hot mould will allow alloy to flow easier also.