hey Russ.
i hope you don't mind. i want to show you something.
first a disclaimer. i use tensioned coils via the gizmo because they're easy and pretty consistent.
though... the TMC can easily be improved upon using very simple techniques applied by anyone who bends pipe or bar on a regular basis.
the key is the point where the tension is applied. not so much how much tension is applied. the tension must be applied at the bending point for best results.
for example. the common result from TMC's. see the black arrow where the last wind to the terminating leg finally contacts the mandrel 1/4 turn from straight....
View attachment 418542
in a TMC, that last 1/4 turn is assumed to be part of your coil... (and perfect diameter as per the rest of the coil)
now that video may or may not be ideal.

or the ideal coiling method.
but it does show a close contact point that produces a much tighter coil with a near perfect termination wind that aligns with the rest of the coil.\
one of my first coils when i was mucking around with the protank family of grief...
notice the terminating wind is facing you and is the same diameter as the rest and nestled right with them.
what i'm suggesting here...
make 2 coils back to back.
first one... do a super swamper
next one... same thing... but pinch the coil after the first turn or two
take macro photos of the two at the last wind and compare how the leg comes off.
also notice which one grips the mandrel better when pulling it off.
let me know what you find. i could just be crazy, ya know. Mac seemed to suggest so when i brought it up in the protank thread where the TMC seemed to originate.