Air Arms TX200 ProSport piston stroke length

Discussion in 'Piston & Spring' started by kt83, Jun 7, 2019.

  1. kt83

    kt83 New Member

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    Just to clear something up; does the Mk2 TX and ProSport have 84mm or 96mm stroke? Or is it just the Mk2 TX that remained at 84mm piston stroke.

    I were told that post year 2000 all TX and PS went to 96mm stroke, if so what's the general consencus this makes to a .177 shot cycle set at 775fps 8.3gr?

    I mostly use a Mk2 PS that I've replaced the stock AA main spring with Vmach replacement mainspring guide set with Vmach parachute seal plus I've removed the steel top hat and that now feels quite snappy despite the assumed longer stroke. So with a highly stored energy mainspring such as the Vmach type, am I right in thinking that the increased action speed makes up for a longer piston stroke?

    Many thanks.




     
  2. Nick G

    Nick G Active Member

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    Never shot one , but did hear that the early prosport had the shorter stroke / stronger spring of the mk 2 TX, I also heard they had problems with the cocking lever breaking, as the cocking effort is much higher . Removing your piston weight could result in slamming , test with 8.4 and 7.9 pellets you want it to be making a tad more power with the light pellets than the heavier ones to ensure its bouncing a little .
     
  3. kt83

    kt83 New Member

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    Never shot one , but did hear that the early prosport had the shorter stroke / stronger spring of the mk 2 TX, I also heard they had problems with the cocking lever breaking, as the cocking effort is much higher . Removing your piston weight could result in slamming , test with 8.4 and 7.9 pellets you want it to be making a tad more power with the light pellets than the heavier ones to ensure its bouncing a little.

    Thanks Nick. I only removed the piston weight due to the Vmach spring has its own sized top hat.

    I'm sure Steve Pope has said it shoots just as well without the weight in place along with advice not to short stroke a PS because of the pre load placing extra strain on the linkages etc.

    I don't think my rifle is slamming though just a bit snappy quite similar to a gas piston.

    Nick can you explain to me how the PS piston weight counters slamming? I thought the weight was there just to get the power up due to PS short barrel and without it piston bounce occurs? Mine shoots at an average of 775fps over 30 shots AA Field 4.52 8.3gr with extreme spread of 17fps.
    If I'm honest, I don't really know if that is satisfactory or not? I'd welcome your opinion if you don't mind Nick. Cheers. Matt.
     
  4. Nick G

    Nick G Active Member

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    If you now test with 7.9 and compare the power in fpe, if its higher its bouncing, if lower its slamming, they shoot nicer when the two pellet weights are balanced. Because yours feels faster/ snappy, doesn't necessarily mean its slamming. If its shooting how you like it, fine .
     
  5. kt83

    kt83 New Member

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    Right ok I'll test it with 7.9gr Crosman Premiers and see where that comes out.

    A useful point to bear inmind, cheers Nick.
     
  6. Gary Martin

    Gary Martin sultans of spring

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    if you tested with 8.44g JSB derived pellets, I would use 7.9g JSB pellets to compare. When I owned an EV2 I tried some 7.9g Crossman pellets and the muzzle velocity was cira what the jsb 8.4g were achieving. The Crossman pellets I tried were tight in the breach. IMHO a like for like comparison will be of greater use.
     
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  7. Malcolm lockhart

    Malcolm lockhart Member

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    I have never been able to get 8.4 and 7.9 close together.
    On a nice shooting gun 7.9 .4 ft lbs up on 8.4,,, and super domes down .2 on 8.4.
    This is setting round about 10.8.
     
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  8. kt83

    kt83 New Member

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    Re. Jsb 7.9gr Yes good point, I'll use them for future testing.

    Gary and Malcolm thank you fella's for your input and advice.
     
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  9. FPoole

    FPoole Active Member

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    I agree, Crosman Premiers in 7.9 have always shot at about the same speed or as much as 20 fps slower than 8.4 Exacts, in my guns, but never faster than Exacts. Yes the early PS had the short stroke, to answer the op question.
     
  10. Nick G

    Nick G Active Member

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    If 7.9 are making more power than 8.4 add a bit of piston weight, open up the transfer port or shorten the stroke a tad, I know the last two are not really practical for most, people. But adding a bit of piston weight is easy enough.
     
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  11. Malcolm lockhart

    Malcolm lockhart Member

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    Must change what I wrote,,,,, miss read notes, figures were for 7.3 falcons, should have wrote....
    7.9 = 10.84..
    8.4 = 10.75.
    As Nick G's post.
     
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  12. kt83

    kt83 New Member

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    I only removed the AA steel top hat because I were advised to do so by Vmach as Steves guide set is matched to the supplied spring.

    My ProSport feels quick shot cycle plus remains fairly well on target when the shot has gone.

    After fitting the Vmach parts I didn't give any time for bedding in and put 30 shots (AA Field 4.52 8.4gr not weighed straight out of the tin) over the chrono with an average velocity 775 and extreme spread of 17fps. Just wondering would this be considered acceptable seeing as this was straight after re assemble?

    Thanks FP, actually I did have a 1996 mk1 beech stocked PS and sold it to fund a new walnut stocked mk2 PS which luckily I managed to source 2nd hand online.

    I was told that post year 2000 TX's and PS had the longer stroke(96mm) Ofcourse in USA the longer stroke allows for increased tuning options but in UK lot's of guy's say they have a bit of a lazy action time.

    I still question whether the mk2 PS in the original stock without the fish scale pattern has the 84mm stroke and the mk3 TX and PS actually has the 96mm stroke action but I suppose I could email AA to confirm.
     
  13. FPoole

    FPoole Active Member

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    The PS I shot had a 2 hole stock instead of the current 4 screw set up. I think the change to the longer stroke came in about 1999-2000. Apparently James Maccari of Air Rifle Headquarters was behind the change from 2 screws to 4 screws in the stock. Supposedly the stocks were breaking around the trigger guard area when there was only the 2 forward stock screws. The MarkI I shot actually developed a crack from the forward trigger guard screw hole back into the trigger housing opening. Didn't effect anything, but it was there.
     
  14. kt83

    kt83 New Member

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    I'd forgot the extra PS stock fixing points which doesn't appear a bad idea but can't say I had that sort of problem with my mk1 PS the beech stock was finished in that dull polyurethane lacquer that won't even polish up well. My mk2 PS walnut stock is reasonably configured and oils up nicely with the original understated chequered pistol grip and fore end panels.

    Out of curiousity FP have all of your TX's been set to shoot 12fpe; I think I've heard you mention before? .177 I take it?
     

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