The 'tit' on the magazine insert also keeps the magazine insert in place.
The magazine insert itself is what keeps the sides of the magazine from being compressed and the floor plate 'locked' in place. Once it has been flipped out of the way, the floor plate will come right off.
You guys who are using C clamps, the Brownells tool, etc... are going to damage your magazine tube and/or insert.
This is such an easy thing - some of you are making it way more difficult than it has to be by inventing new ways in which to disassemble.
CHP Training for VA, WV, NC, FL, TN, and others
HR218 / LEOSA Qualification Courses for VA LEO
NRA Law Enforcement Firearms Instructor / MTC / CRSO
GLOCK Firearms Instructor / G18 and Advanced Armorer
Defensive Training Concepts, Inc.