I have a short barrel golf mortar, the inside barrel length is 2 x the caliber (two times the length of a golf ball) There is no sub-chamber. The mortar is very solid, and gives a very nice report when firing a golf ball. When i want to shoot blanks i have a problem, and that is what to use in front of the powder (FF). In my longer barrel cannon, only a little paper is enough, that's not the case with the mortar. I have tried grass, and solid paper it doesn't work. I have been thinking and casting wax bullets but i would prefer to this as safe as possible. Any ideas?