Flashing on bullets from my Hensley & Gibbs 10 Cavity mould

[FISH4BUGS]

Help! I have an Hensley & Gibbs 10 cavity mould that throws 9mm 125 gr BB RN bullets. When it comes up to temp, you can cast one heck of a lot of bullets with it. I really love it and use it in all my 9mm guns, including 3 submachine guns. I cast with 5lbs WW and 1 lb linotype (allegedly the Lyman #2 formula).
Recently I have noticed flashing (not much but there sometimes but it is getting worse and worse) from the base of the bullets after I whack the sprue cutter and they fall out of the mould. Sometimes it is very pronounced, enough to reject the bullet. It is apparent more on the bullet(s) closest to the handle. I tried adjusting the sprue screw tighter but that doesn't do a thing.
Any ideas what to try to do to fix it?

[David R]

My guess is you have a burr. Probably where the alignment pin goes into the hole. I use a fine flat sharpening stone on the side the hole is in. Hold it flat on the face, go back and forth once or twice and see if there is a shiny spot. If there is, polish it down.

You can also hold the mold closed, and up to a light. Look for light where the blocks meet. If there is, you have some kind of problem holding them open a little.

Good luck
David

[Vly]

David has a good suggestion in looking for a burr. Also look for lead building up on the underside of the sprue plate. I was using a Lyman 4 cavity over the weekend, and found I would get flashing if the mould got too hot or if I held the dipper spout in the sprue hole ( pressure casting ) rather than letting the pour hit the edge of the hole first. By cooling the mould on a damp rag the flashing went away and I got a nice big pile of shiney bullets!

[FISH4BUGS]

The flashing is perpedicular to the axis of the bullet off the base. It is not from the sides of the bullet. I think it might be that I am stuffing the pour spout into the hole. I'll try to let it run in and make sure there is no lead buildup under the sprue cutter.
But damn, those 10 cavity moulds get heavy after a while!

[Texasflyboy]

I have had this problem with my 8 and 10 cavity molds from time to time. Rather than tighten the sprue plate, I tend to let it go loose. The sprue plate should freely swing under its own weight when tipped to the side. Don't tip the mold when the lead is going in or cooling, keep the mold flat or horizontal to the ground. This lets the sprue lay flat against the top of the block.

You probably have a small amount of flash built up on the upper surface of the block or under the sprue plate. What I do to clean my molds is to remove the sprue plate and use 600 or 800 grit wet/dry sandpaper and a thick glass plate. Wet the sandpaper and carefully work the work surface of the sprue plate flat across the sandpaper. Stop when you see shiny metal or no lead. This also helps to sharpen the spue holes a bit.

If you have lead on the upper part of the block, You can CAREFULLY work the top of the block in the same way, the spue stop bolt is the only part you will have to work around. BE CAREFUL. And keep the mold dead flat. It should only take a few strokes.

Slow down your casting if the flashing continues, or keep a soaking wet towel next to the pot. Briefly, from time to time, touch the sprue plate to the wet towel to cool just the spue plate. I often have to do this when I am in long casting sessions. The mold stays hot, but I cool down the sprue plate to get the bases to set up faster and cut cleaner.

Email me if you continue to have problems.

Texasflyboy