shooting in a vacuum raises an interesting question, for me at least - is there enough air in the cartridge to enable all the powder to burn, or is there some inlet of air somewhere? from gcse chemistry i'd hazard a guess that there wouldn't be nearly enough, but i don't know how much of the cartridge is empty space. ideal conditions then would be shooting into a vacuum, say throguh a rubber sleeve type thing, could manufacturers do this and then quote the moa from that?