Bump on Bullet Base

[smokemjoe]

Igot a new Lee 6 Cav. 9 MM mold, I prep. the mold and everthing you do, Cast great, drop bullets right out, But it leaves a hump on the base on cut off, 1st. 3 in the front the worst, I adjused t the bolt that holds down the spruce plate , front and rear. Still no good, got lub plate on cut off plate . I am going to cut a spot out on my return pin in the sizing die now so the bullet will be centered when I size them, My other 2 lee gangs dont do this, How do I fix, Thanks- Joe

[runfiverun]

if it's a raised bump,open the mold sooner.
if its a shifted bump with a tear at the base,open the mold sooner. or sharpen the plate around the sprue holes.
if its a raised rounded base the plate might be bent.
my sizer usually flattens any raised bumps on the base unless the boolit just barely fits it.

[Calamity Jake]

I've been known to cut that bump of with a sharp knife, just don't cut your thumb.

As rfr says check the sprue plate for flatness.

[DLCTEX]

I have good luck eliminating the bump by pushing down on the sprue plate as I cut the sprue with a gloved thumb. Bullplate lube lets me cut the sprue while it is still soft, also.

[MtGun44]

Don't sweat the bump. I grind out the center of the ejector pins of my Lyman and RCBS
lubrisizers a touch so that the pin will seal around the outside even if there is a bump.
For shooting, it doesn't make any difference, but can cause lube leakage in a Lyman or
RCBS type lubrisizer, so if you fix the ejector pins, even that issue is fixed so no sweat at
all.

Bill

[HangFireW8]

Igot a new Lee 6 Cav. 9 MM mold, I prep. the mold and everthing you do, Cast great, drop bullets right out, But it leaves a hump on the base on cut off...How do I fix, Thanks- Joe

If the issue is sprue plate clearance, either your sprue plate, your mold, or both is not flat on top.

Lapping is the fix, and it is easy. Just remove the sprue plate, put some wet-n-dry fine sandpaper down on a flat surface, oil it, and lap the bottom of the plate by moving it in circles. After the first minute you'll see whether it needs it (high spots already shiny) or doesn't (everything getting shiny at once).

If you have trouble keeping the sandpaper flat, you can buy adhesive sandpaper, or use a little 3M 77 spray glue.

Same process with the mold top.

HF

[geargnasher]

+1 to what DLCTX and Runfiverun said.

Gear

[44man]

The bump hurts nothing unless you have a GC boolit.
A cold mold will make bumps.
The biggest problem I see is the wood spruce plate, go back to a steel sprue plate. [smilie=l:

[DLCTEX]

In that it's a six cav. I would first suspect that the mould lacks a little being hot enough, so that you are cutting a cold sprue (obviously not very cold or you'd break the handles, but needs to be softer) or the cutters are dull.

[Longwood]

Don't sweat the bump. I grind out the center of the ejector pins of my Lyman and RCBS
lubrisizers a touch so that the pin will seal around the outside even if there is a bump.


What a great idea.
Thanks Bill.
Should work in my Lee sizers also.