Re: Fly cast without flies is great, but...
Are you trying to shoot the line? Like a double haul? I wouldn't ever try and double haul a nymph rig, you're asking for trouble right there. You should try and master the roll cast to cast that stuff, or try using the water to load the rod for you at the end of your drift to flip the fly back upstream.
Try taking off the bobber, and 2 nymphs and try just casting 1 streamer or something. That heavy and complicated rig is asking for trouble when you're trying to reach 80-100'.