Stevens model 520 parts interchangeability between 12 and 16 gauges

I just bought my second "double hump" model 520 with the suicide safety in 12 gauge (so I can have a matching set). I enjoyed restoring (almost done) my first one but I am having problems finding certain parts for my second. I watch the auction sites and Numrich for parts in 12 gauge but many are getting hen's teeth rare.

I understand some parts are interchangeable between the 12 and 16 gauges (Isn't the frame the same?). I know the barrel is a different size and perhaps the bolt but does anyone else know for sure? I would like to get a better stock and operating handle bar and some other parts but not sure if the magazine tube diameter is the same and if the operating handle bar or action bar is the same length. If many parts are interchangeable then I can expand my searches. Can someone enlighten me?

I read that the 20 gauge versions are vastly different (smaller) so I am not going there. Just 12 and 16 gauge interchangeability.

Thanks for any help in advance.

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

I've always liked these shotguns and one of these days I might buy one.
Interesting ID Guide.

John Browning design, unique take-down barrel in under 15 seconds, built like a tank from drop forged steel, the only plastic is the buttpad, classic styling, looks cool, slam fires 6 rounds in 8 seconds, good ones can be had for under $200.

I don't know why you're waiting, buy a couple now!

Thanks, OKiMarine for the interchangeability help. Now I will expand my parts searches.

Using your guide from the provided link both of mine are post 1924 because they have the later strait slide releases and diamond fore arms (1926?). They seem pre-1928-29 since they have the rocker shell stops, 3.5 inch tangs and trigger housing screws, not the pins. Both are marked as Stevens 520 (not another brand) so using your chart they are both 1926-1928 era versions. Does that sound correct?

The first one I got I did the usual barrel cut down at 19" and installed a tritium sight. Won an auction for a replacement stock with the round pistol grip (the original flat stock was broken in the usual spot where the wood meets the receiver on the right side of the upper tang). and mounted a barrel band sling mount with a 2-screw 1903 Springfield stock swivel. The thing just looks awesome. A true riot gun and fits in my 20" Army tool bag when broken down so it is very stealthy. I have some issues with it that I discussed on another thread.

The second one is currently awaiting parts. The beg problem is the slide arm was broken and brazed back on so I have to spend mucho dinero for a replacement along with an unbroken stock (I wonder why they all break off the upper right side?).

Maxrad,
Trigger housing screws and a straight slide release puts them in the 1926-28 range (with some overlap w/1925). Stevens didn't make clean yearly breaks in their design changes so that's the best estimate i can come up with. I am building a serial number database organized by design change. With around a hundred observed S/Ns so far, the numbers support my evolution model of the 520 (and 520A/620/620A). I'd like to add your shotguns to the list if you don't mind.

Sounds like a nice custom 520 riot, post some pictures. I'm working on a shorty 520 with a cut stock (a legal version of the Bonnie & Clyde 520 whipit gun).

I haven't had the slide/action arm disconnect problem that others seem to have had but I have seem lots of them w/ that broken piece on the right front of the stock. Just picked up a 520 20ga w/ a repair in that very area.

OkiMarine I just sent you a PM. If I can get a way of sending you the pictures direct you can see for yourself. I am only leery about keeping them on a picture-hosting site. If you send me a way of receiving them, I am game.

You should do a picture search for Stevens 520 "riot" or "trench" versions and see why we like them so much (if you haven't already). My homemade riot version has an instinctive feel to it and looks like it means business. The second one I am about to restore I got for 85 bucks so I can afford to put a little into it to bring it back from the dead.

Here's my 520 riot, a 1938-39 Western Field 35. I Dura-Coated it a flat black. One sag on the right rear of the receiver, but it looks way better than when I started.
http://www.shotgunworld.com/bbs/cpg1...6/IMG_2097.JPG

http://www.shotgunworld.com/bbs/cpg1...6/IMG_2098.JPG

I like the Duracoat, purdy.

I am going your route and going to refinish it since I am not a fan of "patina" (even though everyone that sees it says I should just leave it be). I just like the darker finish. I will do one and see how it goes.

Are you going for sling mounts?

Conrad,
Originality is preferred for unaltered guns, but once you cut the barrel, change the stock and do everything you've done then all bets are off. A collector is no longer interested in the gun and the value is in it being a cool looking, fun shooter. I'm impressed with the Dura-Coat, it is really tough stuff. I used one of the disposable kits with its own sprayer. If I did it again I'd just buy the paint and use my old airbrush. I would have had less problems with sags and splatters, the disposable sprayer doesn't give an even coat without a lot of work and a couple quick clean-ups and reshoots before it dried. But, the finish on this gun was heavy patina with some bad rub marks, now its uniform and great for a trunk/HD gun. I'm not going to go with sling mounts, thought about it but I like the clean look.

Well I won an auction for a 16 ga operating handle bar to replace my 12 ga broken one so I will know soon enough if the sizes are the same. The other find was that the long screw that the lifter pivots on was bent slightly jamming the action. I could not figure what was the issue with it until I started turning the screw slowly until the action worked, so now I know. I ordered two new ones from Numrich.
I also practiced finishing the cut-down muzzle so it does not look like a chop job bur factory. It is nice and round now awaiting a bead sight.
With the gun cut-down I got a new weight of 7 pounds, 2 ounces without the sling swivels and sling.

OkiMarine, PM sent.

As an update to this thread I took OkiMarine's sound advice and purchased a 16 gauge slide with action arm (operating handle bar) for my 12 gauge 520 (1926-1928 version). It worked wonderfully and I only had to lightly file the slot that engages with the bolt carrier which took about 2 minutes.

So, yes it is true that many parts are interchangeable between 12 and 16 gauges and in my case the slide, wood forearm, action arm, and magazine tube are indeed interchangeable. This makes parts searches much easier and in some cases cheaper.

Good luck to everyone on their restorations.

Conrad,
Great to hear everything worked out! On a side note, I do not know the size of the magazine end cap screw off the top of my head. I'd suggest taking it to your local hardware store where they have those screw sizing templates and checking it for diameter and thread size. Also from your PM, I have not had a loading problem like that. Could there be a burr on the inside of the mag tube end? The mag tube housing on the barrel is tapered to allow shells to make the transition but there could be a small lip if the tube is off center for some reason. Have you checked to see that it is not the shell stop in some way blocking the loading of the shell? With the rocker shell stop used in this era there is adjustment that can be made in the forward set screw at the front of the receiver on the right hand side.

Well, I am Duracoating my first one a parkerized color while I am finishing the repairs on the original stock doing glass bedding and making the repairs as invisible as possible. I recrowned the muzzle the hard way and tapped-in a bead sight. I also bought two new nickel magazine cap screws from Numrich and painted both parkerized color (both of these shotguns will be the same color only one will have sling mounts, tritium sight and the older round pistol grip stock while the other will not).

So far so good. I am practicing my airbrush skills on the one and will use half the paint on the other when finished. It is currently curing.

Thanks for the advice about the occasional sticking rounds in the magazine. I am not getting any trouble putting rounds in the tube only that sometimes the brass rim gets caught between the magazine tube and the barrel extension when cycling and only a shake or small tap of the sticking round is all it needs to dislodge. There are no dents in the tube and it is clean but I will double-check for a burr and being off center. This problem has nothing to do with the shell stop as the round gets stuck further up between the tube and barrel so we can rule that out (this happens on both buns BTW making me think this is more common than not). It is not that much of an issue except that it makes reliability a factor if I ever needed it for defense. I just wonder if anyone has had this issue and if there is an easy solution (like polishing the barrel extension, etc.).

Conrad,
Great to hear your project is turning out so well. Post some pictures when you get the chance.

I have not had that loading problem on my guns from that period. I just got a set of B's 12 gauge snap caps (light blue) to diagnose cycling problems, much safer than live rounds. I suggest getting a set, not expensive and Amazon has them, they will allow you to pin point the problem safely.

Been doing other things and not working on my 520 set as I would like. My current irritating issue is camouflaging the wood stock repairs on the first one but it is getting better, I just need lots of patience. I am prepping the second one for painting and will start this weekend if all goes well so it can cure this week while refinishing the stock for that one (round pistol grip version) and turning the diamond-checkered forearm into the smooth trench version now that the barrel-side crack is fixed with JB Weld.

Yup, I have 4 very expensive full-metal snap caps I use for cycling diagnosis and practice and 4 more of the cheap plastic ones to stuff in the top of the magazine to give more spring pressure when needing more than 4. I have found that the cheap plastic ones break too easily on the extractors so I don't use them much any more.

Since I have "cured" several quirks with these guns now, I am confident that I will figure a way around the magazine issue after I polish for burrs, polish the barrel extension and check for proper alignment then I will see if the issue still exists, scratch my head, and take further measures. I cannot work on this until I get the paint cured and everything put together on both so I can compare. They are both currently at the point where the action is like butter (even with Duracoat on the action arm) and I am getting more pleased every time I move ahead. You should see the faux Parkerized finish, it looks great.

I am taking pictures of the process of each one so I will share the photos when I finally get around to a hosting setup.

Well, I finished both of the 520s and cannot be happier.
I took them to the range for testing with a bud of mine and after he fired my first build he said he had to have it so he bought it from me (I will keep the second build for myself). We ran both on 00B until we got sore. Shooting with the trigger held down is very fast once you get used to it. The first shot likes to make the guns automatically cycle the second round just using recoil so you have to hang on with a firm grip or this will surprise you the first few times.
Now that the testing is over, I will find a nice military sling for it and call it good.
BTW the Duracoat "Parker" finish is a dark grey Parkerized look that really fits well with these.

Conrad,
Post some pictures and show them off.