The most valuable HD Military pistols will have stamped on the left side of the frame, above the trigger guard. If it doesn’t have this, it is a commercial model or a post-war export return. The best examples have crisp, deep stamps that weren't buffed off during a arsenal refinish.
Disclaimer: While Hi-Standard factory records are well-preserved, no publicly available database is 100% complete. For definitive authentication, consult the Hi-Standard Collector’s Association or purchase a factory letter from the current rights holder (John Stimson’s archive).