Lyman 4 cav. is giving me grief

[Ballard]

I'm having a ton of trouble getting filled out bases, and pinholes in this Lyman 4 cavity. I don't understand what is causing it. Same alloy, same temp with different moulds work perfectly. Any ideas?

[Calamity Jake]

Sounds like a venting problem under the spru plate, take a fine sharpening stone and apply a VERY slight bevel along the top inside edges of the mould faces.
That 4 cav mould is pretty big and soaks up heat pretty fast so you need to get it pretty hot to get good fillout, try uppen the melt temp(750-800°) see if that helps.
Try fluxen real good that may help get rid of the pin holes. Your going to get pin holes from time to time, that just part of casten.

[GabbyM]

What he said. and
Use lots of flux when you encounter a metal problem like pin holes. When I get stubborn to clean metal I break out the white lard. put about 1/4 tsp. in a 20 lb. pot and stir well. you'll have a big fire with lots of smoke. After about five minutes when it's done smoking and you've skimmed off the gray stuff. do it again until you quit getting junk out of your alloy. Don't forget to scrape the sides of the pot.

[runfiverun]

your not getting your mold hot enough, try putting a giant sprue on the top