I think there should be a compound part listing of the 'Projectile Launcher
Part, Cannon Base 2 x 4' (2527) and 'Projectile Launcher Part, Cannon
Base 2 x 4' (2533c01).
In other words, the cannon base and cannon parts.
Practical motivation:
When I try to separate these two parts to upload, they FREQUENTLY crack, and
it is quite disappointing. Especially the REDDISH BROWN BASES.
Especially considering they are $8+ parts on average!
Alternate point of view it’s good to find the brittle brown ones before you sell
them so that they don’t break in shipping or so that they don’t break if the
customer tries to take them apart later. You could list one and add a note saying
it’s both but make sure you mention they are still together since they may break
if taken apart