Howdy Maxrad,
Great to meet another Stevens 520 fan. The simple answer to your question is the only difference is the barrels and the breech blocks but everything fits and interchanges between the two gauges (12 and 16): frames, barrels, breech blocks, slides, trigger assemblies, magazine tubes etc. 16 gauges just have a smaller bore and the breech block is machined so the ejectors fit the smaller shell, I have to be careful when I'm doing a mass cleaning and make sure the right serial numbers match up. The 20 gauge is totally different and smaller. The real problem with 520s is finding the right year parts to fit your gun as Stevens evolved this shotgun continually. What years were your two 520s made?
I have built an identification guide that lays out all the changes and the evolution of this shotgun and will help you date yours if you're interested. It's located over on Gun Values Board here:
http://www.gunvaluesboard.com/steven...uide-2617.html
James
Bookmarks