The takedown key also turns the trigger lock pin. If you lock the trigger,
you need the key or something that can push the lock pin clockwise to "F".
When used for takedown, it's trapped in the grip housing for two reasons:
When the cam latch is down, the key is present until the latch is engaged;
and the trapped key technically prevents removal of the trigger housing.
First I shortened the key, but looped a bright cable tie through a new hole.
Then I made an always-there aluminum key that fits inside the grip backstrap.
Finally, I made an always-there key from a flat door magnet (with the main
polarity in the short 1/16" direction). (It might be an alnico magnet.)
I matched the profile of the original key, but made it only 3/8" long.
It stores on a side of the mag release, close to the grip, where it's
fully recessed. It's hard to accidentally move it, and it sticks firmly.
When this key rotates the take-down pin, it sticks to the pin, but it's
not trapped. I make sure it's stuck on the steel take-down latch as a
reminder to lock the latch when done. (or the slide can come off later)
If the trigger housing is to be removed, this key can just be pulled
out, then stuck on the take-down latch as a reminder.
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