Everybody awake?? Looks like they dropped a Heli-Coil in for the 510 connection??
There's a Difference between a Heli-Coil and a Thread Insert.
A Heli-Coil is used to Repair a Thread that is Damaged. Whereas a Thread Insert is used so a Thread Doesn't get Damaged.
If I have a Soft Metal, like Brass or Aluminum, and need a Thread in it that will get Heavy Use, cutting threads into the Brass or Aluminum is not the Best Approach. Especially when the Depth of Thread is < 2x the Diameter of the Threads. And a Bad Call when the Depth of Thread is <= the Diameter of the Threads. Using a Steel Thread Insert is a Very Viable way to go.
BTW - Can you take a Picture of your Connector. Because none of mine have a Heli-Coil in them. And all of them look like your Run-of-the-Mill Non Adjustable 510 Connectors.