Problem w/H&G 68

[Shome10x]

All,

Problem with a H&G 68...fill nice but the base of the some bullets have a "dish". This can be small or as large as a 1/4 of the base. NOT a bubble in the alloy, but looks to be trapped between sprue plate.

I've tried multiple things including:

More heat
less heat
slower pour
faster pour
checked venting
cleaned 3x, hot soap,solvents, scrub...
Sprue plate and top of mould are FLAT.

I have to reject up to 10-15%... Bothers me since my other H&Gs are golden...

Any clues?

Thanks...Chris G in MO

[runfiverun]

wait a couple of seconds longer to cut your sprue open.

[HeavyMetal]

How "tight" is the sprue plate?

This strikes me as air trapped in the mold. Compare sprue plate tension with some of your other H&G's and see if you can feel a difference.

If the 68 feels tighter you might try loosening it bit and see if the air gets out better.

For those of us not quite so flush we have the same problem with the Lee 6 bangers and wind up using a file to put a very small bevel on the top of the mold block to create one more vent line at the very top of the block.

This usually cure's the problem but I'd "adjust" a sprue plate on an H&G before I got out the file!

[Shome10x]

I forgot about the sprue plate... I've already loosened the plate and it swings freely.

[GabbyM]

you'll need a big enough spur poured atop that big boolit too. Could just be shrinkage with not enough metal in the spur puddle to back fill. The bigger the bullet the larger your spur needs to be.

[Texasflyboy]

you'll need a big enough spur poured atop that big boolit too. Could just be shrinkage with not enough metal in the spur puddle to back fill. The bigger the bullet the larger your spur needs to be.

I second that. Dishes in the base are usually a sign that you didn't fill the trough enough and as the cavity cools, it pulls in a bit. Try leaving more lead in the trough.

If that's not it, my next suggestion would be tweaking the alloy, then the temperature you cast at.

Tom

[hammerhead357]

My worthless 2 cents worth is that its the temp. of the alloy or the moulds or both. I am thinking to hot moulds......Wes