Also, for more proof that 3.5mm and 4mm bullets, with their stand-alone spring section, are a poor design is the extreme performance connectors. Beyond Deans in power handling, you have 5.5mm and 6mm bullets. Those super connectors (easy 100A+ continuous) have the spring built into the body of the bullet.
http://www.rctoys.com/rc-toys-and-pa...RS-WIRING.html
http://www.rctoys.com/rc-toys-and-pa...RS-WIRING.html