H&G 4-Cavity Moulds Finning at the Base

[Grump]

Well into the casting session and despite sometimes tightening the blasted sprue plate screw as often as before every single pour, I'm getting some base fins, especially at the cavity closest to the handles.

Cleaned up one of them before the last session, and noticed that the tops of the mould halves are oh-so-slightly curved like a bad polishing wheel job, towards the joint. The flashing happens when the moulds are dropping barely-frosted bullets.

My technique is to pour from the far hole to the near one, holding the pour maybe a second after fill to ensure fill-out. The moulds are tilted maybe 10-20 degrees and the excess melt runs over the edge.

Wondering if I should just bit the bullet, so to speak, and get the tops machined more flat. Two batches of BHN 12 or so alloy are dropping at 203-205 gr.

These moulds are vintage 1963--at least that's when Dad bought them from...Gil Hebard, I think.

Thoughts, recommendations???

[tomme boy]

I get finning when the top plate is too tight. It should fall away free just by turning it to the side. If not give Eric @ Hollowpoint molds a email about milling the top. He does great work and is super fast.

[runfiverun]

place them on a mirror or other flat surface and look, you'll easily see if they [or just one half] are warped.

[cbrick]

As Run5 says, use a straight edge, a mirror, a steel ruler and lay across the top of the blocks. If they aren't flat it's a vintage mold and well worth saving. I highly recommend Erik at Hollow Point Bullet Mold Service (http://www.hollowpointmold.com/) to resurface the top of the mold. Erik is a craftsman, has the proper machine tools to do it right is very fair priced and excellent turn around times.

Rick