I guess if I was careless I would double check zero but I keep the gun in an aluminum rifle case when transporting.
I found I wasn't using the 223 kit at all actually only changed to it once since I got the 6.8spc kit so basically I decided to have two complete uppers or sell off the 223 kit...
Here is an example... I have 2 T/C Contender carbines with 8 barrels all have scopes mounted so I do not have to re-zero I will double check their zero when I reinstall but I would rather have to only take one shot than many to change the scope adjustment back.
Nov 27 2008 I was working near Monty Lake right at dusk I spotted a 4 point mule deer buck @ 700 + yards, only rifle I had with me was my T/C Contender carbine with a 223 barrel installed it was to late to do anything about the deer that night so I went to my hotel in Kamloops pulled out the Contender removed the 223 barrel and installed my 308Bellm barrel (444 Marlin brass necked down to 308" = 150gr Rem Core Lok @ 2620fps).
In the morning I headed back to where I had seen the deer, in the head lights I set up a target and took one shot it hit exactly where I wanted it to I continued on to the edge of the logging cut where I had spotted the deer put my snow camo on and started heading across the cut to where the deer was the night before with my Contender in 308Bellm.
As I was walking I spotted buck tracks going the opposite direction so I looked behind me and spotted the buck sky lined looking my direction I found a rest shot was 210 yards and the rest is history.
So hopefully you can see why I am set on not having to re-zero a scope/barrel, if all I was doing is blasting at targets at the range I couldn't care less and I would have saved a lot of money on the upper components because I wouldn't have ordered them and just had a dedicated scope for either barrel that I would swap as well the 223 upper will have an older Vari X 11 4-12X40mm AO scope that Korth just did a warranty check on and install an LR reticle for me...
I also do not want or need two complete rifles.