Looking for info about a Stevens 12ga pump model 770

Thinking about buying one, looks to be in pretty good condition, only "issue" is a loose plug spring. If I buy it, it would basically be for home defense & critter killing-not planning on it being in the hunting rotation. I don't know a whole lot about this make of gun other than they were used by MP's & police back in the day. The guy is asking $150 for it.
If anyone could give me some background on the make/model & any advice regarding this particular shotgun-pros vs cons, I'd appreciate it. TIA