Ajay, someone posted on another forum that claybuster was making a 3/4 oz. 12 ga wad so i ordered a sample of them as well as a sample of their 20 ga. 3/4 oz wads. They arrived today and i noticed that the center of the shot cup has a protruding dome in them. It looks to me like it would make a nice platform for full bore foster slugs if the petals were removed.
I don't have a foster slug mold, but it looks to me like you do more slug experimenting than anyone else on this forum so i thought you might like to know about this idea. I don't know if the column of the wads would stand up to a great deal of pressure, but if they would work it looks to me like a great platform to center foster slugs. Claybuster will give you a free sample just for the asking so if you want to give them a try it won't cost you anything.