I've used Nuprol midcaps (yeah, I know - I even started a thread about them), Beta Project EPMs, Dytac Invaders and G&G hicaps in my Specna. The Dytacs are OK but the springs in them are shite (the ones I've replaced with new springs are fine and dandy though), the Beta Projects are very hit and miss but the Nuprols have been pretty bloody good. Plus they're cheap.