There is not much information on the internet about the Diana Model 25 air rifle. It is a youth model, low powered and the originals were made prior to and perhaps during the initial years of World War II. I’m documenting the attempted resurrection of one of these rifles. Perhaps this information will be of use to someone out there.

The rifle came to me with a bent barrel. It’s not the typical upward bend resulting from the barrel being allowed to snap close under the power of the main spring. It is bent heavily to the right, to the point where the owner tells me that a pellet would get stuck in the barrel.

Barrel against the wall, showing decided bend to the right.
Other side of the barrel against the wall, showing the bend.

From the breech end of the barrel, you can see how crooked it is inside.
The breech seal is the old leather type, it appears to be in fairly good shape. We’ll have to hydrate it with silicone oil and see if it leaks when fired after reassembly.
Here are the major components of the rifle. The only thing left to disassemble would be to remove the sights and the piston seal. The sear will be left in the trigger assembly. There was quite a bit of precompression in the spring. The full length of the trigger block was under compression. The spring is 0.110 wire with 30 coils and 0.500 inside diameter. But it appears to be in great condition, no need to replace it at this point.
Left side of the receiver. This picture and the following ones detail the effects of long term neglect in a humid climate. There’s a lot of rust and someone took some coarse sand paper to it some time back. “Rode hard and put away wet” is the way some folks describe this condition.
One can barely make out “Made in Germany” on the left of the receiver.
A lot of corrosion, you can see the scratches from the coarse sand paper. Diana is there, but not easy to make out. The writing is more legible in the pic than it was in person.
It was difficult to remove the piston seal. The screw was held in place by a drift pin. It took nearly 40 inch pounds of force to get it loose – there appears to be a flat on the side of the screw threads that was either filed or merely deformed by the force of seating the pin. Don’t know if I’ll be able to find a replacement or if we’ll appeal to thread locker upon reinstalling. The piston seal is in excellent shape, now soaking in silicone oil to rehydrate and prepare it for reassembly.

A Few Days Later

The compression tube/receiver after being polished to remove most of the rust. There’s still some light pitting and discoloration from the years of neglect. I rubbed it down with some Brownell’s Oxphobluing (I THINK that’s what it’s called) and the resulting finish is splotchy (as expected) but not too horrid – much better than the rust and such.
You can see the “Made In Germany” stamp fairly clearly now.
The piston reassembled. The leather seal sat in silicone oil for a few days to rehydrate after years of being stored. It all went together smoothly.
One thing that “popped out at me” almost literally – the pin that locked the screw in place from the factory got cammed out a bit when I forced the screw loose. Of course, the piston would NOT slide into the tube that way. Used a tool to set the pin back against the screw, it should be good to go now.
The trigger after being sanded to remove the rust.
It blued up nicely.

After a bit of proper lubing of the spring and other parts, the rifle was reassembled. I’d had some doubts about the process, but over on the Gateway To Airguns forum Jon “eeler1” posted a link to a video about a similar rifle. This one is a Winchester 422, and looks like a dead ringer for the Model 25. It’s actually a Diana Model 22, but I don’t know what the differences are between the two models. I’d not checked out the NorthWest Airgun channel in a while. He’s got some other good stuff over there. Worth taking a look if you’re interested in airguns. Anyway, he did three videos on his grandson’s rifle – and that was a big help as when he reassembled he showed me how to do the trigger. I’d been over thinking it and was planning to make a slave pin for the trigger. That would NOT have worked. When I saw him put it together things clicked in my brain and sure enough, it’s not as hard as I thought it was. There was some kind of hangup, but eventually I got it together properly and voilá! The rifle shoots!

I took the first five shots from a free standing position. The light little rifle is easy to cock and shoulder and the trigger isn’t too horrible either. But the sights. Oh, brother! The sights are not very compatible with a tan background, low light and my aging eyes (that were never that good to start with). Still, it seemed like the rifle was shooting to the right still. The center hit on the “bullseye” was a called flier. Pellets are some old RWS pistol wadcutters.
So I ran another 10 shots for a total of 15 and sure enough, it was hitting to the right fairly consistently, and a bit low as well. So out came the precision sight adjuster (tack hammer and brass rod) and the front sight was moved right and the rear sight was moved left and at 7 meters (give or take) the following target resulted.
Five shots at around 7 meters. Not too shabby if I do say so myself. Considering that this rifle wouldn’t even let a pellet through the barrel, I’m pretty tickled with results so far.
Aim small, miss small. I broke out a small black bullseye printed target and proceeded to shoot from 10 meters. Not very good. Hmmm. Moved back to 7 meters and the point of impact raised a bit, but it’s still not a target rifle. Still, I’m tickled to have it shooting.
The Diana Model 25
And the other side.