Nor sure what i said without rereading it (cause i say so much i can´t remember all ) - but i assume that what a machinist calls "shatter" wasn´t my main concern. That kind of "shatter" happens when a not rigid enough machine (mini lathe) is used with a to big tool and/or the wrong feed in any direction, then the small toolpost is flexing down and grabbing again, several times a second - not good.
In mainly all turning processes on this gun the upper receiver will be chucked on it´s barrel frontpart, and stabilized with a living center in the tailstock in the hole for the bolt on the rear end. Due to that the most of the receiver is not chucked firmly.
Be carefull and don´t use to much rounds per minute, and with MGCs with a massive barrel all should go fine. But there are also MGCs with a bore, so the barrel is a tube, if that get´s machined to thin it can be thrown out of the lathe due to the rounds per minute - maybe against the wall behind the machine, maybe against your chest or head. It can be done, just not with faith and fun, you should know what you do and where the danger is.
For those who want to read the thread with my Hero/MGC buildup: http://www.therpf.com/f9/han-solos-a...6/#post1698180