Google search resulted in this....
H&R catalog from 1971 (page 37)
H&R Commemorative Pistol Set
H&R is pleased to introduce a Commemorative Pistol
Set in honor of its 100th anniversary. Only a limited
number of these semi-automatic pistol sets have been
produced in serial number sequence from HR 1 to HR 2000.
The set consists of a double action pistol with
interchangeable matched barrels and magazines in .380
caliber and .22 caliber long rifle. A distinctive gold name
plate and gold trigger accent each pistol. Matched
barrels are identified with the pistol's serial number. Each
pistol set is packaged in a custom fitted, velvet lined,
wooden presentation kit with lock and key and will be a
welcome addition to any sportsman's collection of
limited production sporting arms.
http://chris.cc/hkp7/PDF/HK4.pdf