Alan, if the skirt collapses due to breech pressure rise, you can easily turn the plug down a bit to increase the skirt thickness. Of course doing this will increase the weight again. Your idea of decreasing the depth of the skirt is a good one. Foster slugs have too-thin noses and usually flatten out into disks or break up when hitting something hard. Good idea. (I still prefer round balls - easier and faster to cast and the right size for any bore - just order the correct RB size from Jeff Tanner)