G'day, 
          Any feed back on the use of the above? I find it works rather well , a friend has. concerns re safety of use ,says it is made of carbon and some phenolic substance which is rather toxic!! 
           What are your experiences , opinions, re the use of the above material as a filler in BP CASES breach seated .

Kind Regards Mal,  in Aus .

Some time ago I think it was Mal that suggested floral foam to me as an option for filling the airspace between the powder wad and the base of the bullet when breech seating. 
After thinking about it I feel there is no doubt that it will alter the physics of the initial shot cycle. 
Because the foam has a mass and compressive strength that is greater than the airspace it is replacing it will transfer greater force immediately to the base of the bullet the instant the wad begins to move. The transferred force would increase proportional to the increase in compressive strength of the foam as it is being crushed. 
In short the compressive strength of floral foam seems insignificant but it is a magnitude greater than air and would move the curve towards a more gradual transfer of force. 
Whether that's good bad or indifferent is case by case I would think