I have a model 12 in 16 ga. which I will keep forever for sentimental value ... it was my grandfather's. From what little research I did about model 12's, I know that there are a ton of them. They were produced from 1912 to the 1960's. However, the earlier the model, the more valuable it may be. Try to find out how many 12 guages were made in and around 1921 with the same features as your own. If it's relatively rare, and the condition is good, I'd keep it. If not, and you won't use it, and you're not attached to it, you might as well sell it and use the money for something new and interesting.