The British called it Sleeving, some didn't like that term & began calling it Monblocking, which was even more in error than was Sleeving. When you bore out the chamber & insert a turned blank then the old stub is Sleeved, but it sure didn't turn into a monoblock. Nothing wrong that I see in keeping terminology to its correct meaning. there is simply no way three, four or more pieces brazed together meet the definition of Mono.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra