Of all of the sidelock guns on the market, the CVA and Traditions are probably the guns that rank as the worst ones to try to remove the breech plug.
The breech plug is not only screwed into the rear of the barrel but, after this is done, a cross-hole is drilled and threaded and either a drum on a percussion gun or a plug on a flintlock is firmly screwed into it.
This results in needing to remove the drum or plug before any attempt is made to actually remove the breech plug.
You can see my drawing of this type of breech in the upper right hand of this picture.
The only reason for removing a breech plug IMO is to rebore and rifle the barrel or to get a stuck ball with a hole thru its center out of the bore.
(There are several good ways to get a "dry ball" out of a barrel that do not require removing the breech plug).
Anyway, it is best to consider the breech plug on all muzzleloaders as a fixed part of the barrel that is not meant to be removed.