I have raised a blister that will put your left thumb out of commission entirely for 2 weeks on a shotgun barrel, it was a mossy 500 and it bit me HARD. Granted the shotgun and ammo were free of charge, a 'generous' uncle Sam let me have some fun. Ever shot 600 rounds of magnum buckshot in less than an hour all by yourself? LOL, I am not nearly that tough anymore, as I get older and dumber things like that are less and less fun. Shot 1911's until blood dripped from both elbows a couple times too back then, beavertails are optional and ammo is on my dime now......
Heat shields are not just cosmetic, but circumstances where they are needed could easily be considered 'extraordinary'. The heat shield on 99.95% of shotguns are purely cosmetic. A 590 with bayonet fixed and the heatshield and all sure looks cool too.