HRA rear sight
 

If I have a elevation knob with HRA and a windage know with (just) DRC . Is this correct for a 5.5mil ? or 5,508,000 ?

Yes.

From the Battlerifles.com site:



"Early original HRA rifles had rear sights with elevation pinions marked HRA and windage pinions marked DRC. Sometime in the 5 million serial number range the windage knob was changed and marked HRA-W."




JAS beats me to it again.

Better to ask than to be sorry later. Been there and done that.