What is this?

[Jomibe]

I have an old Remington 580 single shot 22 that I bought used a couple of years ago and then just put away. I recently got it out to see about fixing it up a little bit, and I discovered that where the "loading platform screw" is supposed to be (this part: Loading Platform Screw Gun Parts | 90180A | Numrich Gun Parts) I discovered this:






Where the screw is supposed to be is a hard plastic substance. It seems like it was put in there wet and dried into place. The scratches on the finish are not mine. Does anyone know what that is or how I can remove it to put in an original screw?

Thanks.

 

[1911ly]

Someone probably broke the screw or stripped the threads and tried to epoxy things in place. See if you can melt it. If so melt and pick it out. If not, then drill and carefully tap. If you do melt it please do it in a well ventilated area!