When flattening a detent, it is a very difficult thing to get "right"..... you have a RAZOR THIN margin of error between it working and not... if you get the angle of the flat out of 90 to the blade, it causes more issues then it solves. Flattening a detent will also create a significant increase in drag/friction as the ball rides the blade throughout the action's motion.
An easier avenue, to achieve the same thing is adjusting the detent hole size.
What size detent ball and drill are you using? Try going up or down one drill size and see what you prefer. For a 1/16" detent (also works if you are using metric detent balls and drills) With a smaller detent hole , such as a #54, you will get a "softer" lockup in the closed position... and less drag to open the blade. There will also be less impact when the detent falls off the blade near the fully open position.
A larger detent hole, such as a #53... or some folks even go with a 1/16" or #52.... this will create a "harder" lockup in the closed position, and will require more effort to get the opening motion started. This is often the route people take to create that "pop" you mentioned.
Finally, there is a HUGE difference in a detent hole, that is drilled with a regular 118 or 135 degree drill bit, and one drilled with a a carbide, 135 degree, single flute bit, such as those from MA Ford. These bits create a sharper "shoulder" than standard bits, and will give far more of the "pop" versus other drill bits.
All that being said, none of it will help/change anything unless there is a high level of precision in the overall folder build. The higher the precision of the overall folder, the more impact those changes I spoke about will have.
