Under recommendation I purchased a slab of Fiocchi FBlack 81/2 - through my Muller U2 & U3 & have to say these were awesome, I was extremely impressed with the quality of kills "Smokin"Fiocchi f black just saying..........I used some hull pro this weekend I thought they were a bit thumpy and very dirty, I guess cartridge choice is down to personal preference I know someone who can't stand the smell of some powders........ Silence the competition....... www.proshock.co.uk