TX200 Mk1 low power

TX200 Mk1 low power

Postby Wilfy100 » Sat May 27, 2017 3:54 pm

Could anyone suggest a way forward with my .22 TX200 Mk1. The problem is lack of power, specifically with Air arms diablo field 16 Grain pellets I can only get 9.57 Ft/lbs of muzzle energy. Things get better with lightweight RWS hobbys wadcutters at 11.9 Grain giving 11 Ft/lbs. H&N Field Target Trophy at 14.66 Grain give 10.8 Ft/lbs. I would ask readers of this post to believe me when I say that the rifle is in very good mechanical condition. I have fitted a new piston seal and a new genuine air arms replacement spring along with a TBT tuning kit. I have had to use what I believe is a Mk2 spring for the simple reason that genuine specification new Mk1 springs are not available to the best of my knowledge. All the usual suspects for air rifle spares sell one replacement spring that is marked as being suitable for both Mk1 and Mk2 TX200's. I have one of these and careful measurement shows it to be of Mk2 specification, i.e. wound from wire of slightly thinner diameter than an original Mk1 spring. While this would be slightly less powerful than a genuine Mk1 spring my instinct is that this should not make a significant difference (though I could be wrong with that). The really strange thing is that no amount whatsoever of extra washers to increase the preload will raise the muzzle energy. I have gone from one power washer right up in stages to basically everything I could get in including spacers in front of the top hat. The only effect this has is to make the cocking the rifle harder. It does not increase the muzzle energy at all. At the moment I am at a loss as to how to proceed, I have gone back to one power washer as it reduces cocking effort. I think I will settle for using the H&N pellets as I can live with 10.8 Ft/lbs of muzzle energy provided they give me similar accuracy as the air arms pellets.
At the next air rifle club meeting I will test the accuracy of the Mk1 with the H&N's against my Mk3 TX200 with air arms diablo fields's. I have to say that personally I definitely prefer the Mk3 even when not taking into account the Mk1's power issue. I can achieve similar accuracy with both but it just feels easier and less hard work with the Mk3. I have a TBT tuning kit in the Mk3 and power can easily be fine tuned with the power washers, It is just a case of not exceeding the 12 Ft/lb limit which I believe it would easily be capable of. I would think this should be the same or at least similar for the Mk1. I wonder if anyone could suggest something to try, could any owners of Mk1's confirm that 11 to 11.5 Ft/lbs of muzzle energy is achievable with the Mk1 using Air Arms diablo fields. I do not want to go down the aftermarket spring route because I am very wary of these one size fits a dozen different rifle things. I have learned the hard way with these.
Any help would be much appreciated, Cheers Wilfy
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Re: TX200 Mk1 low power

Postby Blackbaronfish » Sat May 27, 2017 10:58 pm

It sounds like the piston seal. Which one did you fit.

Did I mention that I'm the only one to have attended every annual meet since we started
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Re: TX200 Mk1 low power

Postby Wilfy100 » Sun May 28, 2017 5:01 am

I fitted Protek supplies part number M116, TX200 piston seal. I also sourced the spring, the bearing rings and a breach seal from them as well. They had the parts I needed and were reasonably priced.
Cheers Wilfy
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Re: TX200 Mk1 low power

Postby sherlock1963 » Sun May 28, 2017 12:07 pm

As you are getting more power from light pellets it sounds like the piston is 'bouncing' If you add a little weight inside the piston ( MK1 or MK2 springs have collapsed coils and a steel tophat inside the piston) rather than preload washers on the spring guide, that should close the gap between light and heavy pellets.

A standard MK1/2 spring has a 3.25mm wire and between 210 and 225mm free length.

There should be 2 breech seals (BS108 o-rings)
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Re: TX200 Mk1 low power

Postby DESERT FOX » Fri Jun 23, 2017 9:36 am

You say you have fitted a Tinbum tuning kit,do you mean his spring guides?

If you have used his short stroking kit,then that could be your problem.The MK1 +2 had the ideal stroke to start with.
Its the MK3 that benefits the short stroke tuning kit.
Reducing a Mk 1 by 14mm will nobble your power.
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