David is our hammer gun specialists; but from your description I believe you have a hammer gun from 1920. At the time, the company offered three low-end hammer gun models; identical in all respects except for barrel steels which were Royal Steel, Twist, and Damascus. Guns with Royal Steel barrels were the lowest cost, and I believe carried a suggested retail of about $20; but David will see this post shortly and will set the record straight if my memory has failed me again.