Gentlemen, can anyone tell me if there is some rhyme or reason in the engraving patterns on LC Smith Hunter Arms graded guns.

For instance, my research led me to believe that Trap grade guns had trap shooting scenes on the lock plates. However, I find a 1917 trap grade gun, stamped on the barrel, with two Quail back to back on the locks.

All matching numbers on parts so not a barrel swap.

Could any pattern be ordered on any grade ?
O.M