I just bought a Stevens Model 87H to take apart and learn about and tinker on. I have seen no information on them on the internet. The first thing I noticed is the bolt will not pull back all the way so I can push the pin in and lock it into place. Can anyone please help me figure out what may be going on with this? This is my first semi automatic rifle so I do not know a ton about the inter-workings. Any help would be greatly appreciated.