If it is truly a factory 17" barrel you need to get in contact with BATFE as the barrel is shorter than allowed. Eighteen inches is the minimun lenght of a shotgun barrel. If original you can register it with them for a few dollars thus allowing you to legally own a shorter than legal gun. However just because it has a front sight is no indication of original. Any shade tree gunsmith can shorten a barrel and reinstall a front bead. I have studied older guns for 5 decade and while not an expert on the model 11, I have owned a few and studied old Remington catalogs and have never heard of ANY manufacter producing a 17" barrel. My best advice is to disassemble the gun today and bury that barrel until you get a ruling. If my suspentions are correct it has been shortened by a ham handed previous owner. You can buy a junker gun with a longer barrel or simply look for a barrel online. If it was me I wouldnt sleep a wink until that barrel was off my gun and buried. I want no trouble from the feds and a felony will insure you can never own another gun as long as you live. To properly measure a barrel lenght make sure the gun is unloaded then close the action and run a small rigid dowel down the barrel till it bottoms out on the bolt face, then mark the dowel at the end of the barrel, then measure the length of the dowel to the mark. If it truly is an illegal barrel I would dig it up and hammer if flat then throw it into the deepest lake I could find, then find a new barrel.