I just recently acquired an older model semi-auto 11-48. This is actually my first Remington shotgun and I want to make it into something useful for me. I would like to add a magazine extention to it but being that it is older and my lack of knowledge, I would like to ask the group here. Is the thread the same on Remington shotguns from an auto loader to a pump? I don't have a picture of the threads but a general description is that they appear to be about a millimeter in width and flat in shape. Has anyone added one of these on their own 11-48? Any help would be appreciated. Elwood Wanna kill these ads? We can help!