TX200 short-stroke questions.

[ReturnTrip]

Hello, I am looking to convert my US/FAC spec TX200 MK3 into a short-stroke/sub-12 UK spec rifle. My TX is 100% factory and circa 2014, if that matters.

I would like to be as close to MK2 factory spec as possible at first, before trying anything custom.

I need a MK2 piston and a UK spec 12 FPE mainspring. The only place I've been able to locate a MK2 piston is from airarmsspares, part #TX320S (RFD - PISTON ASSY MK 2 (STANDARD)...is there any other place perhaps in the states I could acquire one? I can get the UK spec 12FPE mainspring from pyramyd.

From my understanding, the US/FAC spec spring guide, tophat(steel), and rear guide washer will work with the MK2 piston and UK spec spring and get me close to what I want. Am I mistaken here, or should I be ordering a MK2 spring guide, tophat, and guide washer...if they are indeed different than the MK3 counterparts?

Thanks.

[Roadworthy]

You allude to "in the states" but I have no idea where you're located.  I don't know that the TX 200 Mk II piston differs greatly from the Mk III.  I got a new spring from Air Rifle Headquarters in Maryland, USA, and my Mk III shoots right at 12 fpe with it.  I'd check with them if you're located stateside.  They KNOW Air Arms.  If you're in the UK you may get some really good information from https://www.airrifletuning.com/

[ReturnTrip]

I am located in Oklahoma. Sorry for the confusion.

[Roadworthy]

As near as I can tell Chambers uses the same part number for the Mk 11 and the Mk III piston as well as their seals.  If all you want to do is go to 12 fpe check with Air Rifle Headquarters for the proper spring.  While there you may wish to order a new piston seal and one of their forged front stock brackets.  The original one is soft aluminum and very flimsy - any side pressure while the rifle is apart can easily break it - I KNOW!!  That can take you to 12 fpe all by itself.  If you wish to experiment with a short stroke kit you can easily get one from  https://www.airrifletuning.com/  There are other mods you can make like reducing the compression tube diameter, it just depends on how serious you want to get and how much you have to spend to get there.    Posted by: ReturnTrip « on: Today at 01:51:23 PM » 

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[Brazos]

I will be curious how your project turns out.  I have a MKIII and wanted to shorts stroke it.  You would think people would make all the parts to convert a MKIII to a MKII or MKI.  I ended up doing the Tony Leech kit.  I don’t like long stroke piston rifles.  They produce power but are harder to shoot.  I would rather have a short stroke with just enough piston diameter to get me close to 12fpe.

[ReturnTrip]

I forgot to add my TX is a .177.

[Sqwirl57]

You can buy a longer piston rod from TR Robb and install that easy peasy. From there its all a matter of playing with the spring. I believe I'm using a modified PG4 full power spring in my short stroked TX

[853_okg]

I have done this myself, to short stroke it, all you need is a mk1,2 piston, or custom latch rod. The only place I know of to buy the mk 1 piston is airgunspares.com.
 The 12ft/lb spring does require a different guide. Short stroking should lower power level on its own, close to 12ft/lb. I get 12.6ft/lb running the vortek pg4 HO kit with mk1 piston, it has a very smooth quick cycle, and is very accurate.
Hope this helps.

[PaulK62]

I have done this myself, to short stroke it, all you need is a mk1,2 piston, or custom latch rod. The only place I know of to buy the mk 1 piston is airgunspares.com.
 The 12ft/lb spring does require a different guide. Short stroking should lower power level on its own, close to 12ft/lb. I get 12.6ft/lb running the vortek pg4 HO kit with mk1 piston, it has a very smooth quick cycle, and is very accurate.
Hope this helps.

I've got the same questions as the OP, so thanks for helping out. I checked out Airgunspares.com, and they discontinued the TX200 MKI piston. Are you sure the MKII piston will work?

[853_okg]

Paul,
I'm pretty sure the mk2 and mk1 use the same piston.

[PaulK62]

Paul,
I'm pretty sure the mk2 and mk1 use the same piston.

Thank you, Dirk.

Would the Vortek 12 ft lb kit require a short stroke conversion? I'm guessing yes, unless the dreaded long shot-cycle the UK shooters dislike is a problem confined to the Air Arms factory 12 ft lb springs due to spring tolerances, diameter, number of coils, etc. So, since the Vortek HO spring is brought down to around 12 ft lb when used with a MKII piston, I wonder what would happen with a Vortek 12 ft lb spring/MKII piston combo? Any idea?

[Brazos]

The 12fpe Vortek kit will lower a normal MKIII down the 12fpe.  That’s what I ran in my MKIII before converting over to the Tony Leech kit.  To be honest I should have just left the 12fpe Vortek kit in the rifle as it shot about as well as the Tony Leech kit.

[853_okg]

Paul,
I ran an air arms 12ft spring and top hat in my short stroked TX however I never measured the velocity, but I'm sure it was definitely below 12ft. I could have bumped it up a little by adding spacers but the HO spring suits me better. Very quick cycle.
 I also have a Diana D48 that I short stroked to roughly 80mm and it is running a vortek 12ft kit. That combo is running 10ft respectively. It is a very pleasant shooter.

[PaulK62]

The 12fpe Vortek kit will lower a normal MKIII down the 12fpe.  That’s what I ran in my MKIII before converting over to the Tony Leech kit.  To be honest I should have just left the 12fpe Vortek kit in the rifle as it shot about as well as the Tony Leech kit.

Paul,
I ran an air arms 12ft spring and top hat in my short stroked TX however I never measured the velocity, but I'm sure it was definitely below 12ft. I could have bumped it up a little by adding spacers but the HO spring suits me better. Very quick cycle.
 I also have a Diana D48 that I short stroked to roughly 80mm and it is running a vortek 12ft kit. That combo is running 10ft respectively. It is a very pleasant shooter.

Thanks for the info, guys. As you might have guessed, I've already purchased a yet-to-be-installed Vortek 12 ft lb kit before reading this thread, and then I realized that without short-stroking, I might not be happy with how it performs. At least with the higher-powered factory spring, the shot cycle is snappy.

I guess I'll install it without the MKII piston and see how it feels. If need be, I'll short-stroke it. Based on what Dirk experienced with his Diana 48, the 12 ft lb Vortek will probably drop to 10 ft lbs, which should be fine. My Walther LGU does 10.5 ft lbs, and it's one of my most accurate airguns.

[Jim-in-UK]

I have short stroked Mk.3 TX200s with longer piston rods, with piston head extensions and, at a cost of pennies, by inserting an 11mm length of 25mm Acetal rod with a central 3.6mm hole and an o ring set in a groove. The latter, christened the 'Jimplug' by a retired engineering friend, costs just a few fps compared to the more expensive options.