Testing a Diana model 23 breakbarrel air rifle: Part 5
by Tom Gaylord
Writing as B.B. Pelletier
Diana 23 was a find on Gun Broker. The finish is bad but the gun works well.
This report covers:
• An update
• Today — disassembly
I started this report back in September 2013 — 16 months ago. I’d purchased a Diana model 23 breakbarrel rifle off the Gun Broker auction website for $30. With shipping, it came to $50. We discussed cruising Gun Broker for airgun deals yesterday, and this is one that I got.
This rifle is really a Winchester model 423, which is how Winchester had Diana mark all their air rifles (in the 400-series, with the Diana model number being the last 2 digits). Most Winchester air rifles are .22 caliber, but this one came as a .177, which is more appropriate to its small powerplant.
I tested the rifle’s power for you in Part 2, where we discovered that it shoots RWS Hobby pellets at an average velocity of 381 f.p.s. I have no experience with Diana 23s, but I expected to shoot that lightweight pellet in the mid-400s. So, the rifle seemed a little slow to me.
But it did shoot JSB Exact RS domes at an average 452 f.p.s., which is about spot-on what I expected. The powerplant may be okay, and it just doesn’t like Hobbys for some reason. I won’t know the state of the powerplant until I disassemble the rifle.
I did discover that this rifle shoots best when the pellets are seated deep instead of flush. The difference is rather dramatic. And the trigger-pull is a very heavy 7 lbs, which is almost double the rifle’s weight of 3 lbs., 11 oz. Anything that can be done to reduce that will probably help the accuracy.
The stock on this rifle is in really nice shape. After a rubdown with Ballistol, it shines as bright as all my other Dianas. So nothing needs to be done to the wood, and aren’t we all glad for that?
While the bluing is off the metal in a really major way, the part of the spring cylinder that can be seen is still smooth metal. It’s not pitted by any rust. The barrel, however, is deeply pitted on the outside, though bright and shiny with deep rifling inside. I was going to have to take off a lot of metal to get it ready for bluing.
At the 2013 Roanoke airgun show (that is sadly no longer running), collector Larry Hannusch gave me a brand-new Diana 23 barrel for this project. He reads this blog and had the barrel on hand, so this was his donation to the project. That saves me many hours of prep time! Thank you, Larry!
If you want to see how the rifle looks right now, look at Part 1, where I show a number of detailed photos of the outside.
Today — disassembly
Today, I’ll take the rifle apart and see what needs to be done to the action. Before I refinish the parts, I want to get everything in shape for the cold blue that will then be applied.
To disassemble the gun, the barreled action has to come out of the stock. I remove two screws in the forearm and the front triggerguard screw. The action comes out, but not easily. It feels like it’s been in there since manufacture, back in February 1969.
Remove the stock screws.
Once the action is out of the stock, I’m surprised to see all the rust on the spring tube. The stock had been hiding that for years. Now, it’s time to take the action apart. The end cap comes off first.
The end cap needs to be pulled off the spring tube. Nothing holds it on.
With the cap off, you can see the rear crosspin that holds the inner tube inside the outer spring tube. The front crosspin must be removed first so the trigger blade and return spring will come out of the rifle — or the inner tube cannot be removed.
Once the cap was off the tube, I put the action into my mainspring compressor and tightened the screw. The inner tube that contains the trigger also bears on the spring guide. It stands proud of the outer tube, and putting some tension on it relaxes all tension on the crosspins.
The action is in the compressor, and there’s tension on the inner tube that takes tension off the crosspins.
The 2 crosspins could now be tapped out. The trigger blade swings on the front crosspin, so remove it first. Then, the trigger blade and trigger return spring can be removed from the tube. Until the trigger is out of the gun, the inner tube that holds the mainspring guide cannot be removed from the outer spring tube. This is a different process than the larger Diana rifles, and it’s important that you do things in the right order.
The front crosspin on the left is skinnier than the rear crosspin. It comes out first so the trigger blade and return spring can be removed. That frees the inner tube. When the rear pin is out, it will back out of the spring tube under pressure from the mainspring.
Next, the rear crosspin is pushed out. Now, the compressor screw is backed off and the mainspring will relax — pushing the inner tube and spring guide out of the spring tube until they can be removed.
The mainspring, spring guide and inner tube are out of the spring tube.
With these parts out, I could see this gun was completely dry. There wasn’t a hint of lubrication on any of these parts. Anything the factory had put on in 1969 had dried out by this time.
I checked the fit of the mainspring to the spring guide and found it loose but not overly loose. The other end of the spring fits the inside of the piston rather well, too. So, I won’t be adding buttons or doing anything to tighten these tolerances. I’ll just lubricate the parts with a light lithium grease at assembly. The 23 powerplant is so weak that anything that slows it down would be bad. Also, I think just the lubrication may speed it up a little. And there’s no vibration to speak of, so tightening the tolerances isn’t necessary.
Next, I had to remove the piston; but to do that, the barrel must come off the spring tube. The barrel has a cocking link that is connected to the piston, and there’s no way to disconnect it unless the barrel is apart from the spring tube. So, the next step was to remove the barrel pivot screw.
The end of the pivot bolt is a nut that was stuck on the end of the pivot bolt. I had to make a spanner to engage the two slots in the nut, so it could be loosened from the end of the pivot bolt.
The barrel pivot bolt looks like a slotted screw. Before it will come out, the nut on the other end must be removed.
The pivot nut has to come off before the pivot bolt can be removed. I cut out a screw driver to make a spanner to fit the slots on the nut.
The nut seized on me at the end of the bolt, and I had to use force to get it off. I ruined the nut, but was able to order a replacement from Chambers Gunmakers in the UK.
Once the pivot bolt was out, the barrel came out of the spring tube forks and the cocking link disengaged from the piston. Now, I was able to slide the piston out of the spring tube. The leather piston seal looks very good. While a replacement is available, I think I’ll continue to use this one. I’d oiled it when I got the gun, so it’s soft and pliable.
The leather piston seal is soft and pliable because it’s been oiled for a couple years. It’s still in good condition. So is the mainspring.
The mainspring is still remarkably straight, so I see no need to replace it, either. But the leather breech seal, which in the Diana 23 is around the air transfer port on the spring tube instead of the rear of the breech, is flattened and gouged. It will have to be replaced. Fortunately, Chambers has a new seal, so I ordered one.
This picture doesn’t show it, but there’s a gouge in the seal on the far side of the breech. That cone is what rides over the ball bearing detent that holds the breech shut.
That’s it for this report. The Diana 23 is now completely apart and ready to be worked on. You saw the rust in the photos; and next time, I’ll deal with that. I’ll also remove all the blue and get the metal ready for the cold blue.
I looked at the simple sear and think I’ll just lubricate it and the corresponding piston hook but leave their surfaces alone. They’re very crude; and by stoning, I could remove any hardening they’re supposed to have.
It’s taken a long time getting to this point; but now that we’re here, the rest of the job should go faster.