@BernardSmith, If I understand correctly, you are going move to a 5 gallon carboy before degassing? This appears to indicate before fermentation ends.
IMO, that is an extra work.
At the first racking prior to fermentation completing, I put 3/4 gallon in a gallon jug and the remainder in a 5 gallon carboy (don't own any 6 gallon). The wine sits about a week, at which point fermentation is normally complete. This is the equivalent of putting the wine in a 6 gallon carboy, as I have a large head space filled with CO2. If I owned a 6 gallon carboy, I'd use it instead of the gallon jug.
At the second racking I degas, fine, and fill the 5 gallon carboy, with the excess in whatever size bottles are required.
yup, i keep jugs from a gallon down to a pint, with bungs for all as well as S airlocks, that way when i go 6 gal carboy to 6 gallon carboy i top off with the same must,
Dawg
Early in my wine making career I filled the carboy after the first racking, and the fermentation was vigorous enough that it spurted out the airlock. After the second time this happened, I realized the guy that told me to fill the carboy to the brim was just a bit off on when to fill the carboy. Either that or he didn't mind cleaning up messes ....