Armchair tactician here, but I assume the intent on that barrel was simply to break up the outline. Viewed from the side, against say, a partially wooded background with sky behind, I can see that being somewhat effective. White on top would have been a dead giveaway from the air outside of winter conditions.

I can't recall which, but I saw something else (PzIV?) that had a barrel-specific paint job that made the vehicle look like it was a short-barrel variant when in fact it had a longer barrel.

I would be surprised that the effect of the suns rays on the barrel would have been considered, when dealing with the production/ammunition realities (shortcomings, compared to modern) of that time, coupled with the fact that the friction from a projectile travelling somewhere in the neighborhood of a half mile/second would *rapidly* change the temperature of the barrel on first firing, and every subsequent would increase the temperature far past temperatures imparted from the sun.

Not to disparage the old time craftsmanship exhibited by Western society at the time, simply that the accuracy levels possible (both in ammunition design and machining/casting/assembly) were nowhere near what they are today, tolerances being one large reason. I can see thermal characteristics and temperature of the material being incorporated in design today, but back then, I just can't see it. Is there some historical citation that reflects it was? Not to be argumentative, but I've been surprised before!