Hi James,
I don't know whether it was common on originals, but here are some pictures of muzzle decorations posted previously here on ALR.
Here's one by David Price in his "father daughter project"
This one is an antique barrel owned by g.pennell
This one is the Soddy influenced E. TN rifle by Ken G.
And another by Ken G, Squirrel rifle
I'm hoping others will add more examples. Seems like I remember seeing a muzzle face with little gold stars inlayed around the bore, but I couldn't locate the picture.
-Ron