M14 Ordnance Gage ID?

Awhile back someone posted a photo of some M14 ordnance gages. There was a "L" shaped gage that was covered in cosmoline. I bought some M14 ordnance gages and it has one of the "L" shaped gages. This is a two piece gage bolted together with allen head bolts. The markings A & B and DATA are on the side of the gage. On the top it has COMP. SHALL BE FLUSH OR ABOVE. On the lower plate it has PLACE COMP. ON THIS SURFACE. There are no other numbers or markings on this gage. Any Ideas? Thanks Robert