Lock backs don't flip open because of the nature of the lock. The tang has to fight the locking bar up to the final height that occurs right before it locks in place. Open it real slow, you will feel it the resistance the entire time. Conversely, if you look at a liner lock, once you overcome the detent it is free for a good portion of blade travel (until the tang picks the detent ball back up). Also, you build up potential energy with a strong detent and then once overcome, the blade flies open with enough force to not really be affected by the blade picking up the detent ball right before lock up. My Caly 3 is very hard to flip open, but my Stretch is easier because it is a bigger blade.