TX200 fettling

[Sake-san]

Over the last 12 months or so I have tried various options to make my TX's less hold sensitive for HFT & FT use. The custom fitted Gary Cane stocks have helped a great deal as one would expect. However my short stroking experiments which included longer latch rods, bolt on nose extensions, HW / Walther seals etc. did not provide satisfactory results. I went back to the trusted V-Mach internals which are very, very consistent and smooth but, the hold sensitivity challenge remained.
I decided for one last try using components from Nick Gibney, light weight ally short stroke piston with o-ring seal, spring and sized guides.
With a free day between house guests leaving and arriving I installed the first set this morning into my HFT TX...
Put a couple of hundred pellets through and then did some 10 shot chrono strings, bang on the money at around 246m/s with the barrels preferred JSB Express (just shy of 11.4 FT/lbs) and a string spread of only 4fps!
Obviously the feel is much faster / snappier than with the V-Mach internals but, not as a very pleasant surprise in any way harsh.
I pushed out my spinner targets to 60m and have spent a very satisfying session consistently (87/100) hitting the 4cm target, admittedly in very low wind conditions and with a basic front support rest but, nevertheless something I could not do previously at this range.
So far I am delighted with the transformation and am looking forward to getting the second set into my FT gun.
Highly recommended

[Raj]

Good work !!! Nothing as satisfying as a good fettle

[Sake-san]

Thank you Raj, I need to spend more hours with them assembled practising and less hours with them in bits being tweeked going forward!
Surprised at the lack of interest in the journey, I guess everybody is now with these modern fangled pcp jobs?
I shall hold the Luddite fort until the relief (RAW TM1000) arrives.....

[gary martin]

how did your results go with the standard piston and longer latchrod. the reason i ask is with an aluminium piston you would require a stronger spring or greater preload to get the power. also what spring did you use in your tests.
Gary.

[Sake-san]

Hi Gary
The longer latch rod felt better to me than the bolt on nose approach but, bear in mind my sole goal was to reduce movement / hold sensitivity in the pursuit of hitting more targets and I did not personally measure any great benefit vs the standard approach.
Springs that were /are used (sorry but, I do not have the measurements / specs):
Longer latch rod: AA TX MKII & AA / V-Mach for MKIII
Bolt on noses: as above
Nick G components: as supplied in the kits
i played a bit with power also (circa 10.8-11.4 FT/lbs) but again did not feel a great difference.
I am assuming that the reduced weight of the piston assembly is contributing a lot when combined with the shorter stroke to reduce movement.
The o-ring seal is providing a very tight fps spread (although so was the V-Mach seal in the standard stroke set up), I am hoping it shall prove temperature stable as winter to summer here is typically 5-35c!.

I think that Nick G is registered on here and he seems happy to take time to share his experience and advice.

One final consideration is that I believe (as in most sports) that there is an element of psychology at play, in other words feeling confident and comfortable with what you are using is contributing to the results!. Sounds obvious but, changing to a very fast shot cycle is probably not for everyone!.

[gary martin]

i shoot with Nick in the same comps. he has advised me that the light piston is not really compatable with the pro sport. due to the lighter weight i would require greater preload to achieve the power. the pro sport has a small dia cap screw which retains the cocking linkage to the compression chamber. due to the added force placed upon the cap screw he has adviced me to stay with the std piston. i am considering a latch rod 14mm longer, mk2 mainspring and an o ring seal. i wish to keep the std stock as the pro sport is beautiful. i know a heavier FT stock will help reduce recoil but i dont want to go that way, its smoothness of firing cycle im looking for. the mk3 internals give a long lazy recoil but this affects the follow through. i wish a snappier action so the rifle returns to target before impact, as i want to catch sight of pellet.
thanks for the reply.
Gary.

[Sake-san]

Good luck with the quest, unfortunately I did not retain the longer latch rod pistons or I would have happily sent you one. With the standard weight pistons I preferred the normal stroke V-Mach spring, guides and seal ref seeing the pellet in flight. Strangely and against common wisdom shooting at a high 11.8 ft/lbs, I don't know if that was because it was closer to the designed power of the MKIII (or just mind games). Less than 1cm of pre-load and no power washers etc., the springs were deliberately ordered "warm" from Steve Pope, very, very smooth but, with a faster cycle than standard.

Have fun and safe shooting

[gary martin]

could i ask you, when you tried the standard piston with longer latch rod+ mk2 spring did you use the piston weight or just a slip washer?
Gary.

[Sake-san]

Tried with both a steel top hat (piston weight) and also a delrin one, the steel version (due to length) gave more pre-load but, I could not detect any real difference between the two (other than the obvious power variance).
If you can be patient (not a virtue of mine ) and promise to send it back!, I will post you one of my V-Mach 11.8 sets, I think with the standard piston you will probably be very happy, certainly there is little movement but oh so, so smooth.

[gary martin]

Tried with both a steel top hat (piston weight) and also a delrin one, the steel version (due to length) gave more pre-load but, I could not detect any real difference between the two (other than the obvious power variance).
If you can be patient (not a virtue of mine ) and promise to send it back!, I will post you one of my V-Mach 11.8 sets, I think with the standard piston you will probably be very happy, certainly there is little movement but oh so, so smooth.

thank you for the offer, but at that level i would be uncomfortable. 11.8ft/lbs in your rifle maybe + - in mine. just looking for some additional info before the decision is made. also it takes me approx 3 months to learn differences with my set up regarding major things, 12 months to learn my scope temp variations, dark/light contrast etc.
Gary.