You really are clueless about this stuff.
Not entirely. I at least went back and restarted reading from post #1 and saw what was and what might have been.
According to the linked memo authored by SA Warner of the Secret Service ...
https://i.imgur.com/rk20BhI.jpgThe stretcher in question
"was left unattended for approx one hour" according... to the statement to him by attendant Tomlinson.
That is a long time

Hospital security Wright's statement according to...
https://imgur.com/CIn10To stated that
"It could not be determined who used that stretcher." Further stating that
"The attached bullet was received about 5 minutes before Mrs Kennedy departed for the airport." It was not far at all from Parkland to Love Field. LBJ was sworn in at 2:38 [Dallas time]
Wright said that the bullet "was attached" ... to what? Any clue?