Diana 25 air rifle: Part 2

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1

Diana 25 air rifle
The Diana 25 (this one says Winchester 425) was made for decades. It’s at the top of the youth line of air rifles that were made from the ’50s through ’70s.

Today, I’ll test the Winchester 425 (Diana 25) breakbarrel air rifle for velocity and power. When I shot the rifle, the ultra-smooth firing behavior suggested that it might have been tuned. And a faint whiff of burned grease confirmed it. I shined a tactical flashlight down into the cocking slot and saw the mainspring is coated with a thin layer of black tar — proof positive the innards have been breathed upon!

The second clue as to its past is that the rifle was owned by my friend Mac before I got it. I know he loves this platform and does not fear taking one apart to make it better.

Finally, the trigger is adjusted to perfection. Mac knows how to do that, as I described in Part 1 of this report. The trigger is two-stage with a very long first stage that stops at a definite second stage before breaking crisply at the shot. I would not call it a glass-rod trigger, because the excessive overtravel after the trigger breaks makes it feel less precise than it really is, but if you’ve never sampled a fine sporting airgun trigger, this one would amaze you. The only aspect that might put some people off is that the first stage has to be very long for the second stage to be crisp. You can try to shorten stage one if you like — but then stage two disappears, and the trigger becomes a guessing game.

The trigger return spring on this rifle is heavy enough to give the first stage a 1 lb., 1 oz. pull weight. Stage two breaks at 2 lbs., 15 oz., and I doubt you’d guess it to be that much.

Cocking effort
One reason I love little breakbarrels like this model 25 is their light cocking efforts. This rifle has a ball-bearing detent that makes the barrel break open easier. Then just 14 lbs. of force are needed to cock the rifle. That’s so little that pre-teens will find it easy. Of course, this particular example is as smooth as they come because of the tune it’s received, but even a rusty old relic that’s been sitting up in the loft of a barn for 30 years will still cock pretty easy.

Diana 25 air rifle ball bearing detent
Instead of a chisel detent that has a powerful spring behind it, the Diana 25 barrel is held closed by a spring-loaded ball bearing. It is much easier to open and close the barrel, yet it stays shut when the gun fires.

Remember, this is a .22-caliber air rifle — not a .177. This is a case where the smaller caliber probably would have been the better choice, but folks with large fingers will still appreciate this one for the ease with which it can be loaded.

RWS Hobbys
The first pellet I tested was that old standby — the RWS Hobby. In .22 caliber, this wadcutter weighs 11.9 grains and typically offers the highest velocity of any of the lead pellets. In the test rifle, Hobbys averaged 440 f.p.s. The spread went from 421 to 458 f.p.s., which is a fairly broad 37 f.p.s. range. They loaded firm, as if fitting the bore well, so I expect them to do well in the accuracy test. At the average velocity, Hobbys generate 5.12 foot-pounds of muzzle energy.

From what we learned while testing the Hy Score 801 rifle that has a pellet seater built into the barrel, deep-seating pellets can sometimes increase velocity and also stabilize the overall range of velocities achieved. I tried seating the Hobbys deep into the breech. The result was a large loss of velocity — from 382 to 408 f.p.s. for the deep seating! That tells me the model 25 doesn’t like its pellets seated deep, so I didn’t try it with the other pellets.

JSB Exact Jumbo Express
The next pellet up was the JSB Exact Jumbo Express dome that weighs 14.3 grains. This is a pure lead pellet, and it fits the rifle’s breech very nicely, going in easier than the Hobbys. These averaged 417 f.p.s. and ranged from 414 to 422 f.p.s. That’s an incredibly tight 8 f.p.s. spread across 10 shots! I want to note that this pellet also went deeper into the breech with just finger pressure. That means the skirt was not subject to damage when the breech was closed — something I can’t say for the other two pellets I tested. This pellet produces 5.52 foot-pounds of energy at the muzzle.

The last pellet I tested was selected for a very specific purpose. I’ve found in the past that taploaders that have large holes through their taps — such as the Hakim trainer — need a soft lead pellet with a very thin skirt so the light air blast will flare the skirt out to contact the bore and seal it against air blowby. Even the RWS Superdome has a reinforcing ledge inside its skirt that prevents this from happening. But the RWS Superpoint doesn’t. The Superpoint skirt is very thin, soft and pliable; and it seals better than any lead pellet I’ve ever used. I like to at least try them in low-powered spring guns like this model 25 air rifle because they often give very good results on paper.

In the test rifle, Superpoints averaged 377 f.p.s., and the spread was from 373 to 383 f.p.s., so only 10 f.p.s. The Superpoint weighs 14.5 grains, so at the average velocity the muzzle energy was 4.58 foot-pounds. With the first two pellets as a comparison, I wouldn’t call this a great performance.

How does the 25 compare to the Diana 27?
For no better reason than the fact that I was curious, I then tested my Diana 27 (Hy Score 807) with the same pellets. I figured it would be a little more powerful than the 25, but not a lot.

Where Hobbys averaged 440 in the 25, in the 27 they went 495. The JSBs that averaged 417 in the 25 went 449 in the 27. And the RWS Superpoints that only went 379 in the 25 actually went 458 in the 27 — exceeding the JSB pellets! I think that result was that thin soft skirt kicking in, and the 25 probably doesn’t have quite enough power to blow the skirts out like I mentioned.

Impressions so far
I wish this rifle was still being made so more of you could experience it. It’s a delight to shoot. It cocks so easily, and the trigger is a dream to use. Let’s all hope the accuracy is there, as well. I’m not looking for tackdriving accuracy at 25 yards this time — just nice round groups at 10 meters because the Diana 25 is a plinking air rifle — first, last and always.

31 thoughts on “Diana 25 air rifle: Part 2”

  1. Tom/B.B.
    I have an old Diana model 35 that probably dates back from 1930’s, it is in excellent condition, and it is very accurate. It is a .177, but gives velocity figures in the same range as you found on this Mod 25 .22, between 400 and 450fps, depending on the pellet. I always wondered what is the expected performance for such and old rifle. Is my comparison between your Mod 25 and my old mod 35 a valid one, or am I just going nuts?

      • If I replace the spring, would that affect its desirability as a collector’s piece? Or maybe just a check of seals might be the ticket?
        BTW, Happy Thanksgiving to all readers and to Tom/Edith, for which I am very thankful for. I learn a lot by reading your blog.

    • I know people have probably asked already, but as I see you’re from NJ, did you and yours do alright with the hurricane? I’m several hundred miles up the coast and thankfully didn’t lose power for more than a couple days and only had a few trees down.

      Happy Thanksgiving!

      • HI Guest,

        we were very fortunate to have suffered no physical damage to property or life. Worst case was a loss of power for 10 days but after having lost the basement last year with Irene, I purchased one of the suitcase generators – a Yamaha EF2000i. It’s primary purpose was to power the sump pump but since we received minimal rain, that was not an issue. It was enough (1600 watts) to power heat, lights, refrigerator, internet and TV while using roughly 1.5 gallons of gas per day. I back-fed the house.

        Fred DPRoNJ

  2. Hi All, and here’s wishing all of you a very good Thanksgiving everyday.
    I do like looking at these classic airguns. These are the ones that the two Roberts had me panting for.
    The innovations just keep coming. I stumbled on to this one today. It is a PCP rifle out of the U.K. that has a unique pistol grip cocking action.


    • The Fast Fire 10 is the one with the pistol grip cocking. It is so ugly only its mother could love to look at it. The Phoenix MkII is by far the better looking and has some innovations of its own. ~Ken

  3. I’ve had an RWS Model 25 for about 30 of my 40 years. It’s a .177, but in every other way identical to this rifle. Is this ultimately the same rifle? I’d love to have it tuned and resealed, but have no idea where to look. Ideas?

    • Chad,

      Pyramyd Air should be able to take care of your 25. I believe they have the vintage parts on hand to restore your rifle.

      As far as a tune, all you really need is what I have — a light coating of black tar on the mainspring. That way you keep all the velocity and still get smooth firing.

      PA should be able to do that for you reasonably and they do Diana guns all the time. Many airgun tuners don’t mess with them

      Give their tech department a call at 888-262-4867 and ask for the Tech Department.


  4. Hi All….Have a special family Thanksgiving ! I had a Diana 27, a true delight. Now, a sidebar question. Is the Ruger Air hawk/Black Hawk a Diana 34 Clone or near clone. I read it has a TO6 trigger, the safety is similar ” looking..” but it can be de-cocked.
    Thank you for any ideas..
    Pete in California

    • Near clone with slightly shorter compression tube, rubber buttpad, and articulated cocking link. The Blackhawk stock is more like the older D34P — much sleeker than current Diana. The wooden stock on Airhawk looks less nice than Diana wooden stock, as it appears chubby. The sights on the Ruger are a little flimsier than Diana, and front sight is not hooded; still, they work very well if you get over the fact they are fiber optic. The Ruger trigger is a clone of TO5, but with metal blade. I had one with a crooked hole through bore (run out) that made it unusable for me (windage varied by distance) and I got soured on it, esp. after it spit out a piston seal, so got a D34P, but I think the Blackhawk was a better shooter and a little better balanced; I will get another one when I have time to fool with it.

  5. Thank you BG_Farmer…My Ruger Black Hawk arrives today, if FedEx can find us ( they never can..), leave stuff down on our rural road, a mile away.
    Howie on AAG Classifies builds stocks for them also for $100…Tyrolean, no less, to your order. Anyway, look forward to the Black Hawk. So, TO5 not TO6. Lots of misinformation floating around.
    I like iron sights, so the glow worms may be an issue.
    Thank you, again, indeed.
    Pete in California

    • No problem. I like my D34P, but I still regret not trying another Blackhawk. The Ruger fiber optic sights work very well, and that is coming from me — my main rifle these days is a flintlock with a tiny silver front sight less than 1/8″ high! At 10m, the Blackhawk shot cloverleafs offhand (good for me) with pretty much any pellet I could find. Good luck!

      • Forgot to add — JM tune kits supposedly drop in, and Vortek requires minor modification. The way it shot for me, it didn’t need a tune. There is a sleeve on the mainspring — cock it gently, as I read that some people mess up the sleeve if they slam it home (to engage the safety/sear), which is not necessary.

        • BG_Farmer…well, the Ruger Black Hawk is finally in hand. Yep, FedEx got lost again, and after many phone calls, we finally decided to have them drop it off at the FedEx Kinko’s store, which I will do from now on. Odd, nobody else gets lost.
          The Glow Worm sights are outstanding. The weight is 7 pounds, 4 ounces, higher than Ruger says. The Cocking effort is equal or higher than my Beeman R-1. Not the 30 pounds posted, it seems, and much higher than a Gamo Big Cat 1200 ( .177 ). It will smooth out with many pellets shot. The handling and ergonomics is excellent and I recommend this air rifle. However, that said, at 83 years old, It is going back.
          Thanks for all your help.
          Pete in California

          • Pete,
            Sounds like a problem getting deliveries — I understand, being off the beaten track.

            I remember the effort to break open the rifle was stiff at first but it broke in fairly quickly; I think the actual cocking effort on the D34 was/is higher. But, I’m not 83, and my arms are as big as many people’s legs :)!

            Thanks for the update and sorry it didn’t work out (unless you can talk a grandkid into cocking it at least a few dozen times). I’m glad you also had the same reaction to the sights as I did–changed my view of fiber optics.

            • Thank you, BG_Farmer..Your comments are most welcome. Being a Taoist, bad things lead to discoveries, like finding out how to survive FedEx and decide to use them in the future and also finding out good advise like your advise. I only paid $65.52 including “Shipping”, it is as new, refurbished. Yes, I can cock it. Did it once, and it made a creaking noise. Like an Inner Sanctum radio show of the 30’s.
              I think I mull all this over, and may just keep it and see what develops. This Blog ( well, it is really a Blog Plus Forum…) is of great help .
              Thank you, again BG_Farmer.

              • Pete,
                I enjoy talking about the airguns I know anything about, so no need to thank me. You do whatever works for you; I’ve almost achieved an ego-less self when it comes to airguns and the like, so even if you consigned it to the dung heap of airguns, I wouldn’t take it personally, although I would be a little surprised :).

                I think there are a couple of things with cocking: 1) the ball detent lockup is very secure; this makes getting the barrel open the first bit more difficult than other types of lockup and may make the cocking effort seem worse than it is. It should stay fairly tight, but it will or can be loosened up a little both with time and lubrication. If the ball is completely dry, a little, tiny bit of moly grease probably wouldn’t hurt it. The one on mine showed oil film, perhaps excessive, so I didn’t add anything while I had it and may have wiped some off. I try not to add any lubrication to anything for the first tin unless it is absolutely necessary (due to detonation dangers), but if required, sparse lubrication is not wrong. Otherwise, I think it is a matter of technique, giving the barrel a sharp rap to break the lock initially, then it should cock at least at the rated weight after a few strokes.
                2) The “ghast” sound on cocking should go away after a few cycles as the piston seal seats. BB has referred to some piston seals as “self-lubricating” and I think this one is one of them, a bit like the D34. That assumes that the noise is coming only from the seal and there is no grating of metal(bad). It has been a while, but I still recall the Blackhawk being quite easy to cock after a relatively few shots, whereas the D34P that replaced it is still on the stiff side after a tin or so of pellets, though just as quiet now as the B’hawk. I attribute the perceived difference to the articulated cocking link on the Ruger, but that is just a guess.

                Anyway, you may as well try it out some while you’ve got it. The return period is quite generous.

                • Well, nothing like the chisel detente on a Webley Tomahawk( Turkey) just a beautiful and fine air rifle, but I wore gloves to use and snap the barrel open. The chisel really was a perfect lockup. And smooth cocking throughout the stroke. If you can find a Tomahawk made where ever, at a reasonable price, you should consider it. If anything, just to hang on a wall and look at.

  6. Well, there’s no shortage of good airgun tuners it seems (as opposed to gunsmiths). Mmmph. Sadly, the RWS Hobby which performs so well for me in so many different guns is not doing the job with my Walther CPSport. You need the finger strength of a gorilla to work that trigger with the Hobbys. So I’m on the hunt again for a new pellet.

    Thanks for the advice yesterday about my unfortunate situation with the Enfield No. 4. B.B., yes, a 0 number bolt head exists because I’ve got one. That’s one reason I bought the rifle. Bright bore and 0 bolt head told me that I had a rifle in pristine condition, and that’s what the gunsmith indicated over the phone. I was just salivating at getting the rifle back and going out to shoot, so you can imagine my feelings. Robert from Arcade, I had encountered that issue before about the bolt head not being screwed on. I thought that might have been the problem when I originally could not insert the bolt into the rifle, but it just turned out that I didn’t know the procedure for the MkI* variation. (I checked and the bolt head is screwed on properly now.) Here the plot thickens. I learned how to insert the bolt with the aid of a well-informed person I met online who recommended this gunsmith that I went to. So, you see, I was trying to be smart about this! I avoided the lunatics down the road who couldn’t keep track of my gun while transferring and tried to go with a good outfit. They seemed convincing too. They spoke reasonably well and were careful of details like putting little zip ties on my gun case to keep it closed. But their final product sucked. Fred from the DPRofNJ, yes, please do send the info about your friend the gunsmith. You can write me at gufgo24@yahoo.com. I wish you guys could be here in person to feel how stiff the bolt is and appreciate the outrage that has been done.

    It gets worse. I called up the gunsmith the other day. First, in a diplomatic way, I asked about his figure for a chamber cast that was a full .7 inches short of the recommended OAL length in the Lyman manual. He admitted that it wasn’t exact because he took the measurement without the bolt being closed(!) I thought gunsmiths had some method of doing this. Otherwise, what does one need them for? Then, he admitted that he didn’t really take a chamber cast but just measured the length of the fired case! Madness!! In what universe would I need a measurement for a fired case when I could do that myself and when the unresized case length does me no good whatsoever? Then I asked him about the sticky bolt. He said that’s part of the rifle design and that there was probably some part that needed polishing. No no no. Not unless some part of the rifle magically unpolished itself during its visit to him because it worked fine before. Clearly, there’s nothing more to be done there.

    It is so crazy that in this nation which is positively flooded with information about guns in magazines and online that it is so hard to find a gunsmith who knows what the heck he is doing. I have tried and you cannot go very far online without finding negative evaluations of just about every gunsmith with some description of incompetence.

    Well, they are messing with the wrong man! >:-| My purpose now is to find a great gunsmith who can treat my gun the way Tennessee treats Herbie, the Love Bug. This feels biblical: If there be one decent gunsmith in the United States….


    • You need the finger strength of a gorilla to work that trigger with the Hobbys.

      Does that model use the 8-shot “revolver” magazine (which is what my CP99 takes)? If it does, check that the pellet does not extend out of either side of the magazine. I know RWS Super-H-Points are too long for my CP99.

      He admitted that it wasn’t exact because he took the measurement without the bolt being closed(!) I thought gunsmiths had some method of doing this.

      There are Go/No-Go “gauges”, but they aren’t the cheapest thing around ($30 each: go, no-go, field [aka: run-away]), and even a gunsmith may not want to buy a set for cartridge that isn’t popular (at least in his work). But on a rimmed/belted cartridge, that only measures the bolt-face to rim/belt. Nothing regarding the shoulder length.

    • Matt 61: I’m not sure I’m understanding the problem with your rifle, but here’s some of my own observations based on my use of .303 rifles ? You don’t check headspace with a chamber cast. You can easily make your own chamber cast with cero-safe alloy which is available from Brownells. It can be remelted and reused over and over again. It melts with low heat and shrinks little. You can also check your headspace by using a newpaper shim laid on top of the cartridge head and try to then try to close the bolt on it. Too many,or to thick a shim tells the story of excessive headspace. First, remove the firing pin parts and extractor from the bolt. Close the bolt on a factory cartridge, there shouldn’t be any resistance. Add shims until the bolt will only close with force on the cartridge. If the shims used ,measure more than about .005 in thickness, the gun MAY have excessive headspace. This is a rough backwoods way of determining if a gun maybe has unsafe headspace if you don’t have gauges, but you have to remember that factory cartridge rims will vary a bit in thickness. If you have doubts use a proper go-no gauge. In my experience with the SMLE’s I have found that like all rimmed cartridges ,if headspace is a tad over spec, you will experience a slightly backed out primer on a full power load. A SMLE Mk 3 I used at one time would slightly back out it’s with primers with full loads. If you only neck size your cases and use moderate loads, your case life in the .303 will increase. One of the best fun loads I used in my .303’s, was buckshot (about .311-.313 dia,) over 8.0 grs of unique powder. Super quiet and deadly on starlings to about 30 yards. Raise the muzzle before you shoot or use a case filler, like a wee pinch of dacron fiber atop the powder. You don’t even need tools or dies for that load. Another was the swagged hollow based .32 wadcutter( for the .32 S&W long cartridge) seated about a 1/4″ out of the case mouth. You do need to slightly bell the case mouth for that one and you need loading dies for seating the bullet. This one was very accurate for me. Better stop now or I will get flamed for to much specific firearms talk.

      • Robert,

        I sure hope you won’t hold back on the firearms talk. I don’t own a British .303. Nor do I reload. But I read your post with great interest. You’re one of the many posters here who knows what the heck they’re talking about, and always has something informative an interesting to say.


  7. B.B.,

    Interesting numbers on your 425. My copy has a new OEM spring and averaged 470 fps (ES 16 fps) with Hobbies and 418 fps (ES 5 fps) with the Superpoints. However it hates the 14.3gr JSB pellets; the 16 grain version shoots much better – both in the velocity spread and accuracy. It also does well with the cheap Crosman Hollowpoints.

    I agree that “tuning” is not really needed on these airguns. They are very nicely finished from the factory – there are no rough edges to be cleaned up. As you said, a thin layer of tar on the mainspring is all that is needed. Properly lubricated they cock and shoot very smoothly. They are also pretty easy to work on, aside from the trigger assembly.

    Paul in Liberty County

  8. Robert from Arcade,
    Flamed, for helping out Matt, if that happens I’m going to take my ball home and never play with you guys again!

    I hope this is a problem that is simple to fix. I feel the same way when I let the professional mechanic screw up our vehicles because I’m to lazy or busy to do it myself. The good news is that you will learn some stuff before this is all over and will share it with all of us.

    Happy Thank Giving!

  9. I love and still have my 25 from the late 60s and do still have the original Winchester gun magazine that advertises there guns plus a couple pages of there airguns at the time.Glad i kept the book!I havent rebuilt it yet bit have all of the parts to do so if needed as she just keeps shooting with some tlc.

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