Reporting on the TBT Maxi Pro with short stroke kit in my new TX200

shergar said:
The largest top hat in photo came out of a non FAC gun but certainly does the rifle no favours sub 12.
For FAC. Air Arms use a different spring, still 230 mm in length. 21 mm OD but with 3.1 mm wire. even stiffer than their Mk2 spring.
I currently run their FAC spring in a HW80, after removing a number of coils.
Weight of top hat, if considered alone, will increase recoil. So will an increase in spring forces, if considered alone.
Less weight more spring or more weight less spring is the choice amongst other factors, including amount of pre load etc.
In a previous post I referred to a ,"Sweet Spot". In at least one gun, AA got it right.
AA also sold a different spring, higher spring factor, for their MK1/Mk2 production based on the shorter 81 mm stroke.
The fact they decided on a different, softer spring for the Mk3 suggests they gave some consideration to the matter.
I've yet to see a post claiming a Mk2 spring will improve a Mk3 on anything other than a short stroke conversion.
Having previously trod the path of replacing steel top hat and upgrading spring. In my case using a Titan 10 with 2.96 wire. I now recognise that AA have also done their testing and come close to getting it right.
Where the Mk2 stroke benefits over the Mk3 is the extended latch rod allows an extra 14 mm of space for the compressed spring, increasing longevity. Compared to HW 77/97 where original springs can be fully functional after 20 years, the Mk3 spring,especially in 177 with the extended top hat, has a shorter life span. I replace any that have shortened to less than 220 mm.
Don't bin your Mk3 springs. In a Tony Leach, 22 mm reduced cylinder conversion they will need cutting.
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John knibbs have the large steel top hat listed as the required one for FAC
 
Jay Butts said:
Great info, so am I correct in thinking the longer spring with the short stroke in my MK3 will be under less strain in .177?
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Unfortunately, short stroking with a piston head extension does not create the space, ie 14 mm, that is gained by a longer latch rod.
Picture shows Mk3 and Mk2 pistons with latch rod extending 31 mm and 45 mm.
Most new springs will shorten slightly as residual stress from production get redistributed, then will perform well until, after many cycles, fatigue sets in.
20241104_130830.webp
 
shergar said:
Unfortunately, short stroking with a piston head extension does not create the space, ie 14 mm, that is gained by a longer latch rod.
Picture shows Mk3 and Mk2 pistons with latch rod extending 31 mm and 45 mm.
Most new springs will shorten slightly as residual stress from production get redistributed, then will perform well until, after many cycles, fatigue sets in.
View attachment 601449
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I recognise the MK3 on pic with the longer latch rod. Is there any mileage in a narrower comp tube and piston to reduce inertia or is that what the lower diameter kits already do?

I’m all about reducing recoil now…. Can you tell? 😂😂😂
 
Wessex said:
If you have a look at TBT videos and his web site, Nick explains the reasoning behind short stroking a mk 3.
I am sure if you contacted him you could get chapter and verse form the man himself.
Jay is yours a .177 or a .22?
Keep us posted on developments.
Cheers
Julian
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Hey Julian, so sorry I missed your post mate. Mine’s a .177 and I will keep reporting back on this thread buddy. 👍👍👍
 
Jay Butts said:
I recognise the MK3 on pic with the longer latch rod. Is there any mileage in a narrower comp tube and piston to reduce inertia or is that what the lower diameter kits already do?

I’m all about reducing recoil now…. Can you tell? 😂😂😂
Click to expand...
The Mk3 is the one with the shorter latch rod, meaning it has to be drawn back further to latch. Creating the longer stroke.
Piston head extension pushes back whole piston unit relative to compression tube, so cocking stroke and latch up is same as Mk2.
One click on ABT not 3.
 
shergar said:
The Mk3 is the one with the shorter latch rod, meaning it has to be drawn back further to latch. Creating the longer stroke.
Piston head extension pushes back whole piston unit relative to compression tube, so cocking stroke and latch up is same as Mk2.
One click on ABT not 3.
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My mistake… gotcha…

I’m just going to leave mine for a while now to let things settle down. As previously posted, I’ll bet it’s not had more than 100 pellets though it since new.

Thanks for imparting your knowledge, I’ll probably come back to this time and time again.
 
Just ordered the maxi kit for my pro sport tonight, minus the short stroke. I can always add one later if the mood takes me, but reviews seem very mixed..
 
As far as the FAC Mark3 goes, you can rest assured, they shoot very nicely. My Mark3 was set up with a fitted nylatron guide and tophat and FAC spring. No twang and .177 8.44 Exacts at 900 fps. I shot many sub half inch groups at 55 yards, outdoors, off the knee, FT style. I've since put in a Mark1 piston to keep it under 12 ft lbs.
20241109_205859.jpg
 
FPoole said:
As far as the FAC Mark3 goes, you can rest assured, they shoot very nicely. My Mark3 was set up with a fitted nylatron guide and tophat and FAC spring. No twang and .177 8.44 Exacts at 900 fps. I shot many sub half inch groups at 55 yards, outdoors, off the knee, FT style. I've since put in a Mark1 piston to keep it under 12 ft lbs.View attachment 605572
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Wow that shows the right kit and the right person can achieve. Reminder to self., need more practice! Great post by the way Jay. Thanks for the update. I am very lucky to have 3 TXs: Mk1 TX std (previous user tuned, no idea what is inside and will not open it to find out), Mk3 with WW kit and another Mk3 with Deleted member kit. In my own experience the MK1 is the best to shoot, followed by Deleted member one made to measure kit. Yet to try a TBT, one day. Safe and happy shooting. ATB Norm PS,
 
There is a reason professional airgun specialists do not approve of piston extension spacers held on with grub screws.
 
FPoole said:
As far as the FAC Mark3 goes, you can rest assured, they shoot very nicely. My Mark3 was set up with a fitted nylatron guide and tophat and FAC spring. No twang and .177 8.44 Exacts at 900 fps. I shot many sub half inch groups at 55 yards, outdoors, off the knee, FT style. I've since put in a Mark1 piston to keep it under 12 ft lbs.View attachment 605572
Click to expand...
I was always told by those in the know that the tx at 84mm stroke could easily exceed 12ftlb just with the export spring and standard piston seal minus the piston weight. But besides, that group is fabulous Freddy.
I can just about manage sub 10mm groups at 25m benched however our outdoor range is bewitched with strong swirling breeze that annoyingly ruins a nice budding tight group!
TWTSC

TWTSC

www.twtsc.org.uk www.twtsc.org.uk
Tunbridge Wells Target Shooting Club - TWTSC

Sorry to the OP for digress.
 
Jay Butts said:
Haven’t a clue what you’re on about….i only know about the Mk3 and md’s isn’t standard. It’s tuned. No TX200 ever came with Delrin guides…and with that massive spring weight and steel power washers mine produced 10.5ftlb which is the reason I changed the internals.

TBT kit works fine for me. Just thought some might like to know…
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Thanks Jay a great write up.
 
Reading these posts with interest.
I short stroked my HW95K (TBT)
It turned it from a very jumpy inaccurate rifle to a super smooth very accurate rifle

I also have a HW97 KT which I bought used.
I've no ides of the history or if it's been worked on, but it's fantastic to shoot & very accurate.

I bought a brand new TX200 (Ultimate Springer) in laminate & tbh, I'm very disappointed in the accuracy.
I have given it a chance & tested loads of pellets & different hold techniques, but I'm struggling for accurately, it's very jumpy.
Today when I was shooting it, as I was cocking it, it felt a bit graunchy.
I have got to try & improve this gun.
I think I'll try one of Nicks Maxi Pro kits in it. (TBT)
I'll report back how it goes.
 
I'm confused; how many clicks should be heard on cocking a modern standard TX? and what relation does the piston sitting further back in the compression tube(short stroke adaptor fitted) have with how many clicks heard from the side latch?

Edit: I think I've thought it through now. I assume with the short stroke adaptor the comp tube sits further forward in the cylinder upon in cocked state? I'm not all that keen on only one notch being engaged, kinda defeats the object of having a safety device in the first place.
 
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Just fitted the Maxi pro kit to my MK3 TX200. I’d say a tad more accurate but I’m struggling to get the power down. Currently it’s hovering around the legal limit with no Power washers in. There is slight dieseling so I’m hoping it settles down. Has any one else experienced the same? Just after a bit of advice before I think about shortening the spring
 
DonnyJonny said:
Just fitted the Maxi pro kit to my MK3 TX200. I’d say a tad more accurate but I’m struggling to get the power down. Currently it’s hovering around the legal limit with no Power washers in. There is slight dieseling so I’m hoping it settles down. Has any one else experienced the same? Just after a bit of advice before I think about shortening the spring
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i had the same issue with a HW95 with the extension fitted.
Did not want to cut the spring down and find i did not like the short stroke feel.
If i could of achieved the power by doing away with the washers i would of continued.
Also dod not want to reduce top hat height.
 
DonnyJonny said:
Did the power settle down or did you remove the kit?
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Took it out on same day,with ext and no washers could not get below 12lb.
I could of collapsed the weihrauch spring BUT like to keep that in case any new owner wants it.
100% fitted correct,dont know if ext ups power of standard?
 
I guess I’ll put a tin of pellets through it and Chrono it again. Might collapse a coil to keep it legal if no change
 
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