TTI Piston Assembly for HW77 or 977 -A closer look

The product can be found here:

This is what we mean for TTI Piston Assembly.

when you purchase, will ship all that you see in the above picture. A complete package. You just have to drop it in your HW77.

The Compression tube is coated with hard chrome. It serve the duel purpose.

1) Anti rust

2) Anti friction

The piston also having special anti friction coat in both internally and externally.

Both the parts i.e., Piston and chamber are hardened more than 50 hrc. So rest assured, the parts are ever lasting.

And you will have a stunning beautiful shooter.

Anti-friction ring is purposely not done in the front part of the chamber. The reason is simple. After cocking, the breech hole securing the front part of the chamber well. The back part however required to be steady thus we made the ring there.

Some internals.

Carefully machined!!

Just wanted to show the alignment.

This is how it looks like inside a HW77

A detailed look. The piston and the compression chamber aligned properly with a support from the Synthetic ring.

As said before, the breech hole is securing the front part of the chamber properly as a result you can see the proper alignment thus the gap.

Here is a feedback and video provided by a customer:


51 responses

  1. Yes Target tune that piston setup is beautiful. If you had the same setup for the diana 48-54 I may be a customer since I have damaged my compression tube and I am low on power and your buttoned pistons are very nice. The airgun comunity would benefit if these pistons were available for all Diana and Weihrock guns. I know you sell the 48 piston but don’t see the comp chamber. Buttoned chambers would be very nice for cocking. Very hard to button without a machine shop.
    I have used your 34 guides and thought they were loose and kind of short on the oem springs.
    Sorry but that was my feeling. I also bought your seal adapter kit but don’t know how to get the factory screw out of my old Diana pistons. Can you advise on that?

    1. Thank you very much for your valuable comments Jeff!
      Diana has many version. It was very difficult for us to select which one to address. So we decided to address the all time classic Diana 48/52 T01. This particular Diana carefully made except the Piston. There are many thousand owner across the glob having lot of love and respect for this gun. We thought we can give a little smile if we develop something for them. The chamber however is NOT a mandatory parts where HW77 the piston cannot work without the well designed chamber.

      So for mass production, we’ll not make any chamber for diana however we always can take a custom order and can deliver to you.

      For D34 Guide you have taken from us, it is not to be used for OEM spring. But the spring we manufacturer for D34 ( )

      For OEM spring, you must take this:

      1. Hello TTI:

        There are probably 20 times more M48’s with the TO-5 trigger than the TO-1. The audience is a whole lot BIGGER. The guides should compensate for any differences in the comp tube, dont you think.
        If you can take one CUSTOM order then why not mass produce 20 of them since it is a matter of Economics.

      2. Hi warren,
        YES, I agree and therefore we are in a process of making piston for T05 & T06 as well.

  2. Can I order one with Jeweling… like on this one.. 🙂

  3. Hi

    Your kit is well made, securely a definite step up about tuning our Weihrauch HW77/97 !
    As soon as possible I will purchase one !

    Thanks for your care


  4. Congrats Target Tune – You’ve done it again! Marvellous engineering / precision that would lead to excellent performance. The finish is awesome! What a way to go!

  5. Does the 77/97 piston kit come in both 25mm & 26mm versions to cover all models

      1. 25 mm would be popular in UK as a retro fit part in place of the std 26mm unit. The 25mm piston & compression tube are no longer available from Weihrauch and used parts are in demand. Look forward to when you do make the 25mm version.

      2. Hi Tony,
        We’ll see if we can do something for 25mm HW77 owners.

  6. Chris Carrington | Reply

    Where to I place an order for one of these? and do you supply a 25mm version?

    1. A link is there in the very starting of the report.that will take to to our online shop.

  7. any plans to do anything for the hw80, big market here.

    1. Not only HW80 but also HW35
      In a week, the product will be lunched.

  8. I have tested myself my Hw 77with the Target Tune Kit, WOW what a difference man i don’t know how to say it in words, can i say much much better than the butter smooth. I am Waiting for the FAC spring to test it i hope can push to 19 to 20 fpe. This is my second gun with your kit, the first one was Hw30. The best part is i don’t have to send my guns to professional Tuners all i got to do it is just drop it myself.

    Keep it up Target Tune.

    Also my Hw 35, R1, R10 waiting for the tune kits.

    1. Finally arrived I had ordered the kit. The cylinder and the piston are manufactured with great precision. Derlin’s seals and the accuracy of the measurements, do not significantly reduce the vibration, but the only force on the longitudinal axis.
      The TTS’s cylinder is shorter than the original, but the total volume of air displaced by the piston is the same.
      Before buying the “piston assembly”, I had taken the tune kit for my HW97.
      After over 1500 pellets fired, the whole thing has been lingering and demonstrates an excellent accuracy and consistency in the speed of the pellet.
      I never had the opportunity to try other kits on the market (V-Match), but I think that of TTI a good compromise between quality and price.
      I use only pellets JSB Exact Express. The power of the rifle is absolutely constant. During a test of 50 pellets, the average power measured was 7.64J (+ / – 0.1J).
      Accuracy to 25m is outstanding and it starts to become less constant over 35mt. But you can have fun shooting at the jars and bottles up to over 50m. My record was 75mt … buf just one time!
      Is an excellent product that dramatically improves the performance of your rifle.
      Decreases it slightly the vibrations of the blow and, above all, requires the reactions to occur exclusively along the longitudinal axis of the rifle.
      This allows to better “manage” the stroke and improves accuracy.
      Congratulations for your product.

  9. Chris Carrington | Reply

    I would like to place an order for one of these but when will you be able to supply the 25mm version as I have a tuning kit for my rifle in this size, and I’m not willing to swap all internals just to fit this piston. If you can supply a 25mm version would it also be possible to manufacture a piston to my own specification?

    1. Yes we can manufacture based on your specs.
      25mm version we are not making at this moment. But if the query is high, we can do mass production.

      1. 25mm version please with front piston teflon bearing like your development HW77 piston, and 3.8mm diameter transfer port.

  10. buon giorno!vorrei sapere se per il pistone hw 977 è previsto un anello in teflon anche sotto la guanizione di testa

    1. No and we have given the reasoning for that. Kindly read it again. The explanation is there just below the 4th picture.

  11. Hoping to see a Diana 34 piston soon. I have three D34 all T06 rifles and the roundest piston from Diana is out of round by over 10 thousands of an inch.

    A matched set like the HW77 set for the Diana 54/52/48 T06 trigger would be nice.

    I just ordered the HW77 set today and if its as good as I think I will need at least one more set

    1. Thanks and we hope to see some more query on D34 T06

  12. put your piston and cylinder on my hw 977.Make change the cylinder and now I am very satisfied with the prodotto.a resent!

  13. are you making 25mm piston yet as i would like one and would order from woodfeild gun care
    thanks paul

    1. Not yet. may be will execute the production by end of feb

    2. We have some confusion though. Some people is asking for 26mm with low swept volume and some asking for 25mm with standard swept volume.

      1. have your 26mm pistons got a shorter stroke than a standard hw piston
        thanks paul

      2. 25mm standard stroke or 26mm short stroke, both options are good and work about the same.
        26mm short stroke is probably cheaper to make as all you need to do is make a longer piston rod.
        I would also like the piston to have a front bearing like your development piston has.
        Maybe add buttons to the front sides of the compression tube so that its supported at both ends? Just maks sure the buttons aren’t where the loading window is.

      3. Front bearing is not required in the piston. We are providing seal and that takes care of that.

        On compression chamber, you have a point but if you use ours, probably your perception might change.

    3. Shorter stroke is now available.

  14. do you have a dealer in australia yet or can we just order straight from yourselves plus on your web site regarding the set back trigger for a hw97k it says only available in India only id this correct or am I reading it wrong

    1. 1. No we don’t have any dealer in Australia yet.
      2. We usually don’t ship setback trigger directly to customer.
      3. Other then trigger, most parts we ship globally.
      4. We have couple of customer from Australia too.

  15. I recently Fitted a TTI HW77/97 piston into a 25 year old HW77 that needed a bit of TLC.
    This rifle was firing at a very lowly 640 fps.
    Fitted a TTI piston and tuning kit. its just a simple case of applying some of TTI excellent lubes to piston spring & guide, dropped it in and WOW straight on the nail 770 fps, a extra washer fitted inside the piston and 785 fps using JSB 8.44grn the rifle has now fired approx 150 pellets and the shot to shot fps difference is approx 4- 6 fps.

    You will not be sorry you fitted this kit..

  16. Hi, I have a HW77k serial number 1049600 (late 80’s mk2?) will your TTI Piston Assembly and tuning kit for the HW77 fit.

    1. Technically it should fit as HW not changed their receiver or main body where compression cylinder goes in.

  17. […] tune india —– if you scroll down to the bottom of the page there is a little video aswell. TTI Piston Assembly for HW77 or 977 -A closer look | Targettune's Weblog they also sell the piston seals take a look at their site they do good things with air rifles […]

  18. What is the piston weight in grams of the current Setup? Also what size in mm is the transfer port in the compression tube ?

  19. Is there a 25mm version available yet?

    1. We don’t have 25mm nor we are planning to make any.
      However we have short stroke Piston which is equivalent to 25mm Piston

  20. When will you be taking orders again?
    Thank you

    1. Thank you very much for asking. We are truly grateful for the support and loyalty of such customers as you. As we always say, we exist for our customers and our most valuable assets are them. Unfortunately, it will be sometime before we can start taking orders again.

  21. would love to order as well

    1. Our heartfelt thanks to you for your unflinching support. We are in the process of relocating our base. We will publish in our web page the time from when we will start taking orders.

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