Once you insert the barrel bushing into the barrel it can turn clockwise and counterclockwise but it turns more in one directon so the spring and retainer sleeve can be installed. Oneway it turns shorter so the spring/retainer can't be installed.
You put the barrel bushing into the slide before the spring and retainer then install the spring/retainer.
Don't feel bad i haven't had a 1911 frame apart since the 70's and i asked mikey here how to do it too. Or maybe it was the 80's or 90's, (big brain fart that gets even bigger with old age). I just can't remember lately.....at 50yo i was ok at 61 yo life sucks.