Mike;
At some point, though I don't know the exact date, all the H grade guns came with a scroll design on the lockplates. When you say extra engraving are you speaking of more than this or are you comparing it with the earlier un-engraved H's. In the earlier guns the H was unengraved with the G having a simple line around the plates. On later ones scroll work was added to the lock plates of both the G & H. the H also got a bit of scroll on the top lever while the G also had some on the frame, top lever, tang & trigger guard. This is per a 1913 catalog, I do have some of the engraved H's but my G's are all earlier guns.