I am not exactly sure how to describe this, or what the cause is - perhaps someone can enlighten me.
With the hammer cocked back fully, if you slowly pull the trigger, you hit a point where the hammer is released and it's effectively in DA mode - that is the full spring weight suddenly appears on the trigger and you can release the trigger at that point and let the hammer down gently.
If you continue pulling a slight bit more, it will fire.
It is like the two actions - releasing the hammer and ... um... releasing the hammer to go bang, are out of order.
With the hammer cocked back fully, if you slowly pull the trigger, you hit a point where the hammer is released and it's effectively in DA mode - that is the full spring weight suddenly appears on the trigger and you can release the trigger at that point and let the hammer down gently.
If you continue pulling a slight bit more, it will fire.
It is like the two actions - releasing the hammer and ... um... releasing the hammer to go bang, are out of order.