I also wondered how the nylon insert is removed from the frame once the barrel is installed if you use a larger the frame sized barrel as in your case, Unless there's a split in the nylon that I can't see..
Thanks for the pics & discription of the work involved to change the barrel..
Also wondered were you got those barrel blanks over in Australia?? I have a Buddy that lives in Adelade..
Thanks again!!
Gary/Hk