Finning on a Lee Mold

[Colorado4wheel]

This is my third try at getting a mold that works. It's the Lee 6 Cav, 125gr, 2R mold. Occasionally I get finning on some of the bullets. It's normally #2 and #5. Will Lapping the mold help? Any other suggestions?

[HORNET]

Are you sure that you're not getting pressure on the sprue plate handle when you're casting? That is one of the most common problems newer casters have with them. It's real convenient to grab all 3 handles but bad things happen to boolit quality.

[Colorado4wheel]

Nope, not grabbing all three.

I just took a closer look and the areas that have finning now have lead imbedded into them. It's the nose of each bullet. I was able to pop most the lead off. Some is really not budging. I am getting frustrated now.

First mold from Lee poured really light. This is my second Lee mold. It pours heavy by a little but has this finning. My lyman mold had bad handles and one of the pins got peened. Why cant I get a mold that works. I am thinking of fixing that Lyman and trying it again.

[Cloudpeak]

Are the alignment pins, both male and female, flush or a tad below flush on the mold faces? Do your blocks have plenty of play with the handles so things don't bind up when you close the mold?

I hope you get your mold up and running. I've really good luck with that bullet design.

[462]

Remove the remaining impacted lead, hold the mould up to a bright light source and see if it closes tightly. If any light is visible, Cloudpeak has the answers.

[sagacious]

...the areas that have finning now have lead imbedded into them. It's the nose of each bullet. I was able to pop most the lead off. Some is really not budging. I am getting frustrated now.

One of the most beneficial reasons (but least recognized) for smoking the mold faces is that if any bits of lead get smeared onto the blocks, you can spot them immediately against the flat black soot.

Plus, you'll be able to pop the bits of lead off very easily, as it won't adhere tightly to the smoked surface.

Smoking the mold should be done with a butane lighter for best results. Matches work too, but can leave a waxy hydrocarbon deposit that caused wrinkled bullets for a few pours. The butane lighter works every time.

[Shiloh]

Somewhere on the mold something is hanging up. There is a mechanical block somewhere causing the mold to remain unclosed, hence the finning.

I think you mentioned on another post you found some burrs. Look it over real well.

If you look at a LEE mold under magnification, There are A LOT of burrs!!
Let us know what you find!!

Shiloh

[four eyes]

I agree with sagacious,you need to smoke... and make sure no light can be seen when you hold mold up to a bright light closed.alos make sure you only are gripping the two handles,not the spur handle...four eyes

[Colorado4wheel]

Alright. I had already removed the finning. Just checked it under a Magnifier with light to be sure. What was holding the mold open is some lead that is deposited on the edge of the mold by the tip of the bullets. I soaked the mold and cleaned it with a toothpick to get the stuff out. It's discolored in that area. I am soaking it again to be sure it's not residual lead. I can see the lines from the mold very clearly with the Magnifier. I am not holding all three handles. Just the two your supposed to. Also, when you hold it up to the light you can not see light between the molds. I am going to polish it after casting some new bullets with out finning. I want to open it up a little bit anyway. Any other ideas?

[HORNET]

A light Lee-menting to get rid of the burrs will help you get a consistent cycle going and may let you turn the temperature down which will help reduce the tendency to form the fins. Let us know what you get.
Now then, on that Lyman, take your case mouth deburring tool or a countersink and put a light chamfer on the entry holes for the alignment pins. Use a small punch and drive the pins out of the block from the outside to the inside, clamp it in your drill, and polish the burrs and dings off. Drive them back in from the outside until the mold halves will just close with a little pressure. You should not be able to feel or see any movement between the 2 when you try twisting them together. You may have to move the pins in and/or back out a bit to get it right. It's a matter of feel. Lyman's manual used to explain this better than I do. Again, let us know what you get.
I end up tuning just about every mold that I get, new or used, to get them to run the way that I want them to run. Something to do when it's nasty out.

[Colorado4wheel]

I actually prefer to use the Lee Mold as it's soo much lighter and faster. I didn't realize finning could be caused by too hot a mix of lead. Mine did creep up in temp when I was casting. That lee pot does not like to keep a stable temp.