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Education / Training Testing a Diana model 23 breakbarrel air rifle: Part 6

Testing a Diana model 23 breakbarrel air rifle: Part 6

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3
Part 4
Part 5

Diana model 23 air rifle Diana 23 was a find on Gun Broker. The finish is bad but the gun works well.

This report covers:

  • An update
  • Step 1
  • Rust
  • Step 2: To buff or not?
  • Pits
  • Steel wool
  • I’m not done prepping
  • Cold blue

Many of you are interested in working on vintage airguns. To this point, I’ve shown you how to tune several spring-piston guns and I’ve touched on the subject of cold bluing, but I have not discussed it in detail. This series will go into the refinishing of the metal parts of a springer, including how to apply a deep cold blue that lasts.

An update

The last time we looked at this Diana model 23 breakbarrel, I’d disassembled it and shown you all the bad spots. I said then my plan was to refinish the rifle. Today, we begin by cleaning the parts. I’m only showing the spring tube, but all the steel parts are treated in the same way.

I’m going to tell you everything I do to the rifle, but not in great detail. If the detail is important, like getting a good blue with a cold blue product, then I’ll elaborate; but I doubt you want to read about every stroke I take with the sandpaper.

Suffice to say, the finish on the metal parts of this rifle looked poor when I acquired it. Just look at all the pictures in part 5. But that was nearly all the bad news. The wood stock looked okay. Not swell — just okay, but that means I don’t have to do anything to it. The world of fine wood craftsmen can breathe a little easier.

And the gun tested pretty good for power. These Diana model 23s were youth airguns and never had even the power we sometimes scoff at in vintage guns. The .177-caliber JSB Exact RS dome averaged 452 f.p.s., which I thought was pretty good. And, I noted that the breech seal was flat and gouged out, so with a new seal it ought to go even faster.

Normally, my inclination is to overhaul an airgun without giving its appearance a second thought. But several readers had been discussing the best ways of applying cold blue products, so I thought I would refinish the metal on this gun for you. I also bought a few new parts that will be applied when the time comes.

Step 1

The first step after disassembly is to remove all the old finish. If there’s rust, as there certainly was on this rifle, remove that as well. The metal on this rifle appeared to have had its blue partially removed at some time in the past, because the patches that remained were not caused by honest wear.

I applied Birchwood Casey’s Blue and Rust Remover (get it online or at any good gun store) to all the metal surfaces with a cotton swab. The old blue didn’t come off fast; but with repeated swabbings, it did go away. Getting it off the spring tube took about 30 minutes. I then sanded the surface with 180-grit and 320-grit flexible sanding blocks. That took off all the remaining blue and all of the rust.

Diana 23 spring tube
All the old blue had to be removed from the spring tube.

Diana 23 cap off
This is the rust that had to be removed.

Diana 23 spring tube cleaned
And this is how the metal looked when all the rust was gone.


When I came to the rusty areas, there were two different types. There were areas of surface rust that simply wiped away with one or two swipes of the sanding blocks. Then there were a few places where the rust was deeper. These were scaly and built up, as if the surface of the steel was boiling away. And I guess that’s right, because that’s what deep oxidation (rust) does — over time it bubbles away the structure of the steel.

In these areas, I had to sand longer and harder. The blue remover is also a rust remover, since that is what bluing is — a form of oxidation. In these tougher areas of rust, I saturated the metal with the solution and came back repeatedly with sandpaper. Saturate and sand — again and again. In these areas only, the metal is pitted.

Step 2: To buff or not?

When the steel was cleaned of all blue and rust, I had to make a decision. Did I want to buff the metal to a high shine using a buffing wheel, or did I want to work it up by hand? Buffing produces a beautiful mirror shine, but it takes skill to buff a gun part and not change its shape, round the sharp corners or obliterate the stamped letters and numbers. I do not have the skill, so I decided to do the work by hand. That would be slower, but also more under my control.


When you remove the heavy rust, the metal underneath is often pitted to some extent. The question becomes, “Do I try to buff down to smooth metal, or do I leave the pits?” This is a question of personal taste, but I’m on the side of leaving the pits. There’s a way of removing these pits, and I’ve shown it to you in the past. You can weld new metal into the pits and grind/file/sand down to smooth metal again. Top restoration companies do this as a service, and you can pay thousands of dollars for it because of all the labor involved.

Diana 23 pits
These are minor pits in the metal. I advise leaving them alone.

Nelson Lewis combination gun Otho welded gun
Both these guns were equally pitted. My friend Otho welded the top one and filed the surface flat, then had the gun refinished. It looks perfect! This job took one year of his spare time — probably a man-month of effort!

If you blue over the pitted metal, the pits won’t show as much. That’s why I recommend not grinding down the metal. Few people are skilled and patient enough to do a good job. While small pits won’t show up, any change in the contour of the metal caused by excessive buffing and grinding will stand out prominently.

Steel wool

The first thing I did was buff the spring tube with 0000 steel wool. Our friends in the British Isles call this steel fur, which is a more accurate name in this case. This extremely fine product was able to shine the spring tube to a nice level. I could have called it quits at this point and simply cleaned all the other parts the same way, then applied the cold blue. But I want to take this project farther, because all the work that’s put in now will be reflected in the depth of the final finish.

Diana 23 Winchester markings
This is what the Winchester marking on the spring tube looked like before I began.

Diana 23 Winchester marking
And this is how the Winchester marking looked when all the rust was gone.

I’m not done prepping

The next step is to sand the metal parts with sandpapers of progressively finer grits — 400, 600, 800, 1000, 1200 and 1500. After that, I’ll polish the tube with steel polish and see where that takes it. If it isn’t shiny enough, I’ll hit it with some 2000- and 3000-grit sandpaper and polish it again.

Cold blue

When I feel the metal is sufficiently smooth, I’ll apply Blue Wonder cold blue to all the steel parts. Blue Wonder is different than any other cold blue. It’s tougher, deeper and blacker. It’s not simple to apply, but it is straightforward. When this is all done, this little Diana will hopefully shine again!

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

68 thoughts on “Testing a Diana model 23 breakbarrel air rifle: Part 6”

      • Reb
        I can cock my FWB 300s with one finger. It’s nice to have a easy to shoot springer in the stable.

        It’s just amazing all the different spring guns out there that are nice to shoot but people get hung up on trying to figure out just one gun.

        I’m glad I have the 300s its definitely a pleasure to shoot.

        • GF1

          I’ll second that on the 300S! Awesome rifle to shoot!

          Been hearing grumblings about favouritism and neglect from the other rifles in the cabinet since I got mine. LOL!

          Feeding it JSB Exact 8.44 grains pellets and getting around 640fps – it is still breaking in after its tune-up. Bonus is my local supplier is having a sale on the JSBs – $8.00 for a 500 count tin so I bought a couple of pounds of them to keep me in pellets for a bit. (The HW100 & AR20 like them as well.)

          The 300SU is nice and stable at its weight for target shooting but I think I will make a maple thumb-hole “sporter” stock for when I want to go for a walk about.


          • Vana2
            I have been meaning to ask how that 300 was doing but been buisy with all kinds of stuff. You know how that is.

            But sounds like your happy with it so far. And making a stock for it sounds cool.

            Oh and I’m still shooting the JSB 10.34’s in mine. It’s shooting them dead on at 600 fps. The gun has actually sped up since I have been shooting it. It’s about 50 fps faster now then when I did the ring and tune job. I’m sure the ring has finally seated in now.

            But all in all cool gun. Who needs all that power anyway for those feral cans and paper targets. Well it even takes care of my steel Caldwell spinner nice.

            • GF1

              I got a can of the 10.34’s after you had mentioned you use them but haven’t tried them out yet.

              Been busy myself, my wife got tired of me complaining that a plastic picnic table was too unstable for shooting (she called it “whining”) so she downloaded a set of plans for a proper shooting bench and surprised me with a truck full of lumber for it. Its good and solid (no more excuses) and weights close to 200 pounds!

              The 300 is deadly for pest-control – 26 for 26 – all head shots on grackles and starlings at around a 50 foot range.


        • I don’t think I ever grabbed it other than the middle of the barrel but that 300 you got from Ridgerunner sure sounds like a nice treat!
          And a sidelever to boot!

          • Reb
            They are nice guns. And it is a nice gun.

            It had some scratches on the stock so I refinished it. Some sanding and a oil stain only finnish.

            The metal and the bluing on the gun ain’t bad. I guess if I wanted to make it real pretty I could do a cold blueing on it. Thought about it. J St haven’t yet.

              • Reb
                That’s kind of why I haven’t touched the bluing. We use to have this little dispute about muscle cars when we were growing up. What was going to be worth more money. A unrestored car that might need a paint job but still nice. Or the same car painted. Alot of people nowdays will pay alot of money for a unrestored one owner car. Or one that some body tryed to keep as original as possible even if its got a little rust on the chrome bumper.

                And the stock I wiped it down with stain evey 3 days for about 4 times then stopped. Now I wipe it down about once a month. About like how I do my other guns. I guess just enough and not to much is the way I do it.

      • Hey Reb,

        I have two Slavia 618 rifles – one of them is my first gun I got as a teenager (decades ago) and I shoot it frequently… when I can get it away from my grand-daughter that is.


  1. This is going to be interesting… I tried the Klever (Ballistol) bluing and that wasn’t very good. It’s ok for smaller scratches but that’s it.

    The “heating and cooling off in Diesel” method creates an ok matte finish (or maybve even shiny if you polish the steel really well, I don’t know…).

    It seems the Blue Wonder stuff isn’t easy to get here in Germany but I guess I could import it if I really wanted.

    I hear some gunsmiths and steel goods shops will also blue things for you.

    The FWB300S is really great. I have rearranged my stuff so that I have a real 10 meter range at home now. I’ve also put a Nikko Stirling 3-9×42 on the FWB. It seems the rifle is fully capable of putting all shots in a pellet sized hole provided I can hold it that still. And it *is* easy to cock and very quiet. Not bad for a rifle made 42 years ago.

    The bluing on mine still looks very good, but the stock looks a little beaten. The stickers it had on it told me it was still being used for competitions as recently as 2010.

    I wouldn’t mind having one of those old Dianas, but who is going to shoot all these guns 🙂


    • Stephen
      I got one of the Hawke 2.5-10 side parallax adjust 1/2 mildot Varmint scopes on mine. The scopes a hair longer than I would like because it makes it a little tricky to load. But not to bad.

      But yep them FWB 300’s are good shooting guns. Heck I shoot mine outside bench resting out to 50 yards on a calm day it will shoot very reasonable groups. Mine is a 1976 double main spring main spring gun that have the springs wound the opposite directions.

      But yep fun little guns.

          • What’s up Beazer.

            My phone has its little games it trys to play all the time. Well besides when I mess up too.

            Lucky I ain’t just left it setting out in front of my targets one of these days. Then somebody might report me for phone abuse or something. You know how it is now days.

      • When I opened mine, I found out that it had been serviced by a wannabe gunsmith in the past. It had two identical springs in it.
        Even more interestingly, one of the springs had some coils broken off but the gun shot just fine (probably a little slower).
        When I discovered this, I already had all of the required new parts in front of me (since I had decided that if I open this thing, I’m going to replace all the parts that wear) 🙂

        There is a very good guide on co2air.de (google for “co2air fwb300 zerlegen”) which actually might be worth translating to English. If there is an interest and the author is fine with it, I could do it 🙂

        • I actually have looked at that I believe. I was searching information on the internals of the gun and found alot more info about the 300’s than I thought I would find.

          But one thing that did to mine when I went inside was I got the zero end gap compression ring from FWB. I took the original one out that had the open end gap. I do believe that helped bring the velocity up on the gun without affecting the shot cycle. Oh and of course a little cross hatch on the piston cylinder to get the ring to seat.

          But yep I recommend anybody that likes air gun shooting should get a FWB 300. Or at least shoot one if the opportunity becomes available.

          • I swapped the piston ring as well. I think it hardly had any gap at all after I installed it. I don’t remember what the original one looked like

            I’m not sure what you mean by “cross hatch”.

            • The ring I installed if you look at it from the side has about a 1 mm over hang over the top half of the ring. Same for the bottom half. It kind of looks like a ( Z ) shape gap. Not a straight up and down gap ( l ). Suppose to help have less compression blow by of the air. Some race car engine builder over here use them. Suppose to give more compression with a slower leak down.

              And cross hatch is like a ( x ) pattern you hone or sand lightly into the cylinder bore with a tool that has three honing stones that you put in a hand drill and it rotates in the bore while you move up and down slowly. It is adjustable for tension also so you have to watch so you dont open the bore up. And that also takes any scrathes or imperfections out of the bore. Plus trues the diameted of the cylinder bore back up.When I biult car engines I would take a little transmission fluid and rub a light coat on the rings before assembly. That way the rings would lap or seat the ring to the bore quicker.

              I did the same to my 300. I believe it gives a better compression seal.

        • Hi CptKlotz,

          I would be interested in an english translation if you would not mind doing it.

          I recently aquired a FWB 300SU after 40 years of wanting one 🙂 Any information would be greatly appreciated.

          My rifle is 33 years old. The bluing is in excellent condition and stock is not bad – a few dents and scrapes to be fixed.


          • Vana2,

            if it’s otherwise ok, you’ll probably just have to swap out the worn parts if that hasn’t been done before. Then the rifle will be as good as new.

            I ordered these parts directly from Feinwerkbau:

            1500.121.3 Dichtung (breech seal) EUR 10,12
            1500.127.3 Puffer (piston “bumper”) EUR 10,12
            1500.128.3 Rechteckring (piston ring) EUR 15,59
            1700.129.2 Druckfedernpaar (inkl. Gleitring) (pair of mainsprings incl. link) EUR 18,21

            I’ll ask the authors for permission. If it’s ok with them, I’ll try to translate.


            • Thanks for the information Stephan! Copied and stored for future reference.

              I am glad to see that Feinwerkbau is still supporting these rifles.

              I was fortunate – myrifle had been professionally refurbished by the previous owner and had less than one can of pellets through it. I am still breaking it in.


              • If that is the case, there might be no urgent need to service it.

                Still, translating that guide might be a good thing. Maybe it could even be turned into a blog post if you guys can help me out with some of the more technical terms 🙂

  2. Steel fur? New term to me, I’ve spent over sixty years in engineering and gunsmithing here in the UK and I’ve never heard it called anything other than steel wool.

  3. Hi B.B.
    So you finally brought the old girl out again! Thank you! By the way I really admire your skills Sir. You are so very thorough.I wish I had your patience. Also, thanks so much for the lesson in cold blueing. I always wondered at the process. Can’t wait to see the final result. I bet it’s going to be awesome!


  4. The British call it “steel fur”. They also call a restroom “Water Closet”, the Germans even use that term as you can see in public restrooms in Germany a sign that say “WC”

  5. A little off topic, but I recently bought a Walther Terrus, is it normal to have to bump the joint to get it to open? My other air rifle is just a cheap Gamo Sporter, and it’s unnecessary to do that.


  6. This post reminds me of a passage in a Jason Bourne novel where Bourne explains some brilliant procedure for blowing something up, and his baffled colleague says, “Bloody technician”… 🙂 I’m glad there are people who know how to do this stuff!

    But on the general topic of bluing, my thoughts keep turning to my Winchester 94. Here was a rifle bought in complete ignorance by my Dad in the 1970s for less than $100. It hung on a wall in Hawaii for 30 years with no treatment whatsoever and acquired a fine layer of rust. In attempting to restore the gun, I’ve found out that during this era, Winchester was so down on its luck that it resorted to using a “mystery metal” that does not tolerate standard bluing procedures. The highest authorities told me that even if they stripped the old bluing completely and started from the bare metal, the result is likely to turn purple. The problem is in the metal. And yet the rifle was blued so you would think that somewhere Winchester has a secret formula for whatever they did.

    At this point, the formula is lost, so my thoughts turn to painting. Does anyone paint their guns instead of bluing them? Ordinarily it wouldn’t look as good. Bluing seems to have an internal luster. On the other hand, you could come way short of Michaelangelo and still have a pretty good paint job. Perhaps with the availability of bluing techniques, there hasn’t been a market for this.

    dutchjozef, thanks for the info about the Golden Gun. I had a look at the film last night. The final shoot out is kind of fantastical and part of the generally low production quality of the film. The best part is the dwarf who torments Bond by giggling and calling out, “You only have three bullets left!”


    • Hey what I would do and it’s a personal choice is to brown it. Winchester look really cool that have their blue worn to brown in a saddle scabbard. You can remove the blue, polish it like b b did this rifle, only apply a browning solution like a pensylvania longrifle.
      Follow tried and true methods, it will look like a vintage western American classic. I have a few guns like this and they are great to use as a browned finish is already rusted and won’t be marred by fingerprints or heavy careless use.
      I do this on patchy blued guns all the time and it works for me.

  7. Matt61,

    If I were to ever paint one, it would be powder coat. It is tuff ! Special masking tape that is heat resistant and silicone plugs for holes would be needed. You can use an old electric oven that you will no longer use for food. Tons of colors, matt finish or shiny, even “veined”. I have done it and have seen everything that you can think of painted with it. I would put oven outside or in a garage. Minus oven, you could get a whole set up for 150$ or less.


    • Chris, USA
      One of my buddies makes aftermarket cold air intakes for cars. He powder coats them. Also he does wheels and valcovers also. I have seen some really fascinating work that he has done. Cool stuff for sure.

      But I think I wouldn’t like the idea of putting a barrel in the oven and baking it like you have to do when you powder coat something. Maybe might soften the metal or vise versa harden the metal. Just not sure about that.

      • GF1,

        It’s been awhile, but I think the temp. is only like 450~475F. Most home ovens top out at 500F I doubt metal would be affected at that low temp.. For a barrel, I would shut the oven off and let the barrel cool at the same time the oven cooled, with the door closed, untill cool. I would feel ok doing it.


      • Chris, USA
        Yep I knew that the temperature wasn’t to awful hot. Maybe it is ok but I sure wouldn’t experiment on a good gun. Especially the barrel. Maybe other parts of the gun yes.

        But powder coating sure is pretty though I will say that.

  8. Reb
    Probably a different process. Isn’t that a barrel inserted into the frame? Not sure with out looking.

    I still don’t think I would stick a solid barrel in the oven. Now a shroud like Marauders have. Then yep I wouldn’t have a problem with that.

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