Slug loads with round balls

[Rynnäkökivääri 62]

Looking to starting loading my own slugs, I already cast and reload so adding another mold for slugs would be the easiest way to go. Now I'm wondering about whether I should go with a .690 round ball in a shot cup, or the foster style drive key from Lee?

The round slug looks like it has some accuracy potential if used right, so does the drive key I suppose. I was mostly wondering about the round balls being used on steel targets, might they be too hard on poppers and other metal targets, compared to a foster type slug? Just something I started thinking about, a sphere is hard to deform after all.

Also anyone reload slugs using vihtavuori? Hard to find load data and the loading of shotshells seems to be quite different from metallic reloading, some say you can put a slug in a load meant for shot and go from there, others say you can't.

[DinosaurMikeGolf]

A friend of mine casts slugs using the Lyman mold and I purchase from him. They are 1 1/8 OZ and look like a giant lead BB gun pellet. My particular load is 16.6 grains of Hodgen Clays.

[sargenv]

I've tried both and the Lee foster "key" slug appears to be more accurate in my shotgun.. I was loading it at about 1250 fps to keep recoil down.. I was able to keep shot on the upper a/b zone of a metric target from about 30 yards with my load.. I was actually surprised I even landed the hits...