What is the age of a 7-shot 22 long rimfire Harrington and Richardson revolver serial 507207?

From the serial number and being a 7 shot, I'd guess this one to be an early H&R 22 SPECIAL hinged frame, fixed sight revolvers dating from around 1927-29. Value: In v.good to Excellent - these sell in the $285 to $315 range. Fair condition around $150.