Terry is correct and this is also what JJD wrote on his website concerning the inclusion of the grey gun barrel with the Jagdpanther model:
“The GA-01(121) Jagdpanther is painted in a factory tri-camo pattern and features the choice of cannon barrel painted in factory heat resistant grey lacquer, or tri-camo. During WW2, German tank cannon barrels were delivered to the tank factories and to combat units finished in both grey and Dunkelgelb (dark yellow) heat resistant lacquer.”
Link:
http://www.johnjenkinsdesigns.com/GA01.htm
I switch the barrels out on my Jagdpanther periodically to change up my display a little.