Not sure about the 877's but the Rem 870,11/87,1100,Moss 500,and a couple of others can accept a reciever mount. Some of them are made of plastic like the Weavers and some of aluminum.
Check out the Weaver stock # 48340. The plastic styles are ok for the use of a sight when shooting bird shot but for the use of slugs and a scope I would choose the aluminum mounts. I will add a pic so you will know what to look for. Most gun stores have them as does Wal Fart.
These are installed using the two existing holes in the weapons reciever. NO alteration to the weapon is needed. --- SAWMAN