Photos would help give anyone a better idea of what you have. As a guest you can’t post picture directly, you have to use a url host sight or post a link to them. Sounds like you might have what I have heard referred to as a pig tail,but again pictures along with barrel length(to male sure it hasn’t been cut down) will help get the answer your looking for. As a general guess depending on condition and gauge 250-500 would probably be a  good guess