Recon -
It sounds to me like you don't have your crimp tool set up correctly if your tug test lets the connector fall right off.
A good rule of thumb conveyed to me from someone in the cable making industry is that a crimped connector should withstand at least 10Kg of force (think of a cable hanging in the air and something that weighs slightly more than a bowling ball hanging from it). I've got some RG6 BNC's from Neutrik (NBNC75BTU11) that are so good that the braiding in the coax fails before the crimp does. I wish they would do any 50ohm cable version.
Check out this tool from l-com. It has an adjustable tensioner which allows you some flexibility in how tight your center pins(if not soldered) and ferrules are crimped.
Coaxial Crimp Tool Sizes .100"-.429" - HT-CRIMP03
Paladin, Eclipse, Klein, l-com, Ideal, Comprehensive Video Group, all good tools. I'm sure there are many others but those are the ones I have personal experience with.