I have a couple of different caliber Marlins and all of them are JM's. Question is: why do some of them have the JM stamp with a circle around it and some have just the JM. Does it have to do with the year of manufacture, caliber, the person doing the stamping or what ?? You would think the "famous" JM trademark would be uniform. I wish I knew everything-so I wouldn't have to ask dumb questions.