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Air Guns Diana two forty: Part Six

Diana two forty: Part Six

Diana two forty
The Diana two forty.

Part 1
Part 2
Part 3
Part 4
Part 5

This report covers:

  • Last time
  • Sight-in
  • The test
  • Air Arms Field
  • Trigger
  • JSB Exact RS
  • Many things
  • Integrix scope
  • Discussion
  • Summary

Today I remount the Integrix scope on the Diana two forty to test accuracy at 25 yards. And here is a reminder. The air rifle Pyramyd Air is selling that is listed as the German-made Diana 240 is actually this Chinese-made Diana two forty. I ordered one to test and when the box arrived, that’s what it was. The model 240 is no longer made.

Last time

In the last test at 10 meters the rifle shot well but I had mounted the scope incorrectly and the groups didn’t go where I aimed. They went too high and also to the right of the aim point. I shouldn’t have shimmed the scope rings without test-firing the rifle first. I always shim scope mounts because the majority of breakbarrels I test shoot too low.

I spent about 30 minutes mounting the scope properly before starting the test. Then I sighted-in at 12 feet.

Sight-in

The first shot from 12 feet went to the 6 o’clock position on the bull — half-in and half-out of the black. That’s perfect! I backed up to 25 yards and started the test.

The test

I shot the rifle off a sandbag rest with the rifle rested directly on the bag. I began the test with the forward tip of the forearm resting on the bag, and when I changed I’ll tell you. I shot 10-shot groups.

Air Arms Field

The first pellet was the 8.44-grain Air Arms Field dome that was used for sight-in. These come with 4.51mm heads and 4.52. I shot the 4.52. It took three shots to get into the bull I was aiming at and then I shot ten pellets into a 0.733-inch group (between centers) at 25 yards. In Part 4 ten of the same pellets went into 0.385-inches at ten meters and we expect groups to grow as the distance to the target increases.

The group shown below has 11 pellets in it because I shot it at the sight-in target. The pellet hole on the bottom was made during sight-in. I elevated the scope reticle many clicks which raised the impact of the shots. But as I shot, the group kept dropping. I finished the group but please ignore that bottom hole.

two forty AA Field group
The Diana two forty put 10 Air Arms domes into 0.733-inches at 25 yards.

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Trigger

The trigger is definitely getting lighter to pull, or at least that’s how it feels. It’s a definite two-stage trigger and stage two moves smoothly through an arc with no hesitation. It’s a good trigger.

JSB Exact RS

I tried JSB Exact RS pellets next. They grouped high and to the left of the bull. Ten of them made a 1.274-inch group at 25 yards. In Part 4 ten of the same pellets had gone into 0.533-inches at 10 meters.

two forty JSB RS group
The two forty put ten JSB Exact RS pellets into 1.274-inches at 25 yards. I hoped they would do better.

Notice in this last group that four of the ten pellets are stragglers and six are in a tight group on the left that looks like three pellet holes. That told me something was probably wrong with my hold.

Many things

I tried many things to tighten the groups. Finally I noticed that I was pulling the butt pad into my shoulder tight — a result of holding the tip of the forearm on the sandbag. I pulled the bag back and then the rifle rested without my help. My shoulder was no longer needed. I shot the final group of 10 JSB Exacts into 0.861-inches at 25 yards. This was clearly the best way to hold the rifle and today was clearly not my day to shoot good groups.

Integrix scope

I really appreciate how the Integrix scope adjusts. The adjustments are smooth and positive and the clicks seem very precise. Leapers says the new Bug Buster Accushot Pro has Integrix DNA, so you guys may soon be able to evaluate that for yourselves.

two forty JSB RS group 2
This group of 10 JSB Exact RS pellets measures 0.861-inches between centers. And there is another tighter group of 6 pellets inside the main group. Oddly, It measures 0.498-inches between centers or just slightly smaller than the 10 JSB RS pellets shot at 10 meters in Part 4.

I think I was the one that was off today — not the rifle. I also think that if I went back and re-shot the Air Arms pellets they would also tighten up.

Discussion

We know that the Diana two forty is a Chinese-made breakbarrel springer. But it’s a very good one. I think it’s the Air Venturi Bronco reincarnated. It’s small but feels big in the hands because of the fullness of the stock. It cocks very easy. It’s no powerhouse but it’s a great all-day plinker. I don’t think you need to mount a scope to shoot this rifle, and certainly not one that costs $1,400!

Summary

That’s it for accuracy testing for awhile. Next I want to take the two forty apart and at least see if I can lighten the trigger.

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.

27 thoughts on “Diana two forty: Part Six”

    • Bob,

      Wow! Apparently I write these things but I don’t take the time to read them! I was so sure Part 4 was shot at 25 yards.

      I will correct this, but it will take me some time. Thank you so much!

      BB

      • BB,

        No problem, I only spotted it because I had been keeping an eye out for the 25 yard test of this one.

        I was just looking at a Diana two forty on Sunday in the window of a tobacconist’s here in Wuppertal. It sure is a nice, tidy little gun

  1. Tom,

    If you are pulling the butt to your shoulder when shooting from a rest how much more difficult would be to use the artillery hold when shooting a rifle offhand? How is your offhand shooting practice going by the way and also your pistol practice?

    Siraniko

      • BB,

        which is what makes it so annoying to an IT and general tech enthusiast guy like me. It’s a mystery and therefore a challenge.

        What could it reasonably be? I guess the barrel can’t be too bad, otherwise it wouldn’t be accurate *most* of the time. I don’t like the trigger very much, but somehow I don’t think it’s causing these flyers.

        If I had to guess, I would put my money on uneven piston motion (maybe needs more break-in?) or a breech seal related thing which you already suspected.

        I still have my friend’s two Diana rifles in my care (since his shooting range plans didn’t work out so far).
        I *could* shoot the damn thing some more and see if it improves…

        Stephan

  2. Thanks for this BB! I think you are right about the hold being the culprit. And I agree that the trigger is a good one. Mine is smooth but heavy also. It seems to me that sometimes the release point is unpredictable, but that might just be me not being smooth and deliberate enough. Looking forward to your trigger exploration. Oh, I also had a similar experience regarding the scope. I mounted a BugBuster and it shot high and to the right. I ended up shimming the front scope ring with a piece of camera film instead of making major adjustments to the scope (hoping to keep it near centered).

  3. BB

    So unless I haven’t had enough coffee, today is the first test at 25 yards. If so you may not have been having a bad accuracy day. Instead it seems this rifle’s accuracy potential is just inside one inch at 25 yards. The sand bag placement may have changed the POI location but made little or no difference in accuracy.

    Not remembering that test 4 was at 10 meters is an easy mistake to make considering the volume of work you turn out.

    It will be quite interesting to see if you can reduce the trigger pull required to release the sear.

    Deck

  4. BB,
    I am intrigued about what you will find once you go inside the Diana two-forty, both in the trigger and piston-spring assembly. I share the suspicion mentioned by Stephan that some irregular piston action throws away the flyers. Proper lube – TIAT? – and at worst a little bit of deburring should take care of both issues.

    That said, while I am inclined to fix minor issues and enjoy doing it, this cannot be expected from a beginner to the sport, the presumed intended audience for this rifle.

    Looking forward for the next one.

    Henry

  5. I love these mild, traditional springers. They are a lot of fun and very versatile plinkers, not to mention backyard and basement friendly.

    Overall, especially in light of the retail cost, I find this level of accuracy to be perfectly acceptable for an “entry level” springer that could become the Diana 23 of the current times. I didn’t use “24” on purpose because the 24 had an adjustable trigger, as did the 25. I wouldn’t be surprised if the trigger mechanism on the two forty is similar to the 23. As long as the trigger does not detract from a beginner’s efforts to hit the target, it doesn’t need to to be too light, in my opinion. However a crisp break without too much 2nd stage travel would help.

    All this gun needs is an easy and equally inexpensive way to adjust the length of pull, and this might be a great first airgun for kids. I wonder what the cost of the stock is compared to the rest of the gun. If it is low enough, perhaps a kit could be offered that included an extra stock with a couple of stackable or interchangeable plastic butt plates that would allow someone to change the length of pull from 10 or 10 1/2 inches or so out to 13 1/2 or 14 inches. Or, eventually, an inexpensive adjustable stock that can adjust to fit different kids and on up to adults. Can it be done? I don’t know. I would not shorten the barrel like Diana did on the Model 24J, because that decreases the leverage and increases the cocking effort.

    My last thought based on this rifle’s Diana DNA, is that this could be a base model that a knowledgeable tinkerer could refine for a kid or grandkid and turn it into an heirloom piece. One might mod the trigger, debur, polish, recrown, etc., to wring out all the potential, and it would be treasured as the airgun Grandpa “made.”

  6. Those groups with apparent fliers can’t help but remind me that this gun likely has a chinese barrel. Reminds me of the chinese break barrels that gave me fits (like the Bam B26’s) because they threw fliers no matter the pellets I used. I’d check the crown for burrs and I would give that barrel the infamous Gaylord JB Bore Paste treatment.

  7. I’m still trying to figure out why the replacement o-ring from part 2 (?) did so badly, and what to use to replace the breach seals on my growing collection of Diana break-barrels. Do they all use the same size breach seal? I am making some breach seal tools next.

      • In Part 3, you removed the factory seal, which was not uniformly proud of the face of the breach and replaced it with an o-ring. You said:

        “Now, that isn’t the final word, because I do have a chronograph. We baselined the two forty with the Air Arms Falcon pellet that I’m using for all the tests today. Before removing the factory breech seal the Falcon pellet averaged 561 f.p.s. for 10 shots with a spread of 4 f.p.s., from 559 to 563 f.p.s. With the new o-ring breech seal in place the same pellet averaged 474 f.p.s. The spread was 7 f.p.s., from 470 to 477 f.p.s.

        “Obviously this o-ring wasn’t cutting it, so I added a paper shim that is 0.010-inches thick on top of the transparent washer. Then I popped the o-ring back in place and the average with the same pellet went to 492 f.p.s. The spread was 8 f.p.s., from 488 to 496 f.p.s. This was better but not good enough.”

        Thus my questions above.

  8. After a couple of months of searching and waiting for notifications of the two forty being back in stock, I found a place that says they have them and placed my order today. We will see if I get an ‘out of stock’ cancellation notice or not. I am anxious to see if you are able to help that trigger out!

    Bob

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