Turning a 10J T-12 into a "full power" T-12

The entry level PCP from FX with grown-up performance! Together with the 12 or 16 shot variant, the FX T-12 in all types (FX1000 / FX1000-22 / FX1002 / FX1002-22 / FX1012 / FX1012-22 / FX1212 / FX1212-22). Also known as Logun Solo. The Biathlon model is also based on this platform.

Turning a 10J T-12 into a "full power" T-12

Postby PolarWolf on Fri Apr 04, 2008 10:13 pm

I buy my FX Airguns in Sweden. Except in Sweden the license free airguns are restricted to 10J. So, since I use my airguns in The Netherlands, the first job is to upgrade from 10J to whatever power seems proper for the gun. In the case of my new FX T-12 Match in Walnuty, my aim was 40J. I haven't achieved that yet, it's still stuck at 33J. But here's the story of how I got from 10J to 33J.

The procedure is really a three part operation. First, the "inlet" transfer port in the valve assembly has to be drilled out to 4mm or so. This is the little hole in the black plastic cap. Second, the breechblock transfer port needs to also be drilled out to 4mm. Lastly, a hammer weight, heavier hammer spring and a new screw cap has to be installed. Sounds easy, yet it required the gun to be 90% disassembled.

The rifle as I bought it:
T12_upgrade_1.jpg
Original rifle
T12_upgrade_1.jpg (141.13 KiB) Viewed 20732 times

First, the stock has to be removed. This is easy, just one screw holds it to the action:
T12_upgrade_2.jpg
Stock removal
T12_upgrade_2.jpg (150.7 KiB) Viewed 20715 times

With the action in hand, the fun starts:
T12_upgrade_4.jpg
Disassebly of the action in 4 steps
T12_upgrade_4.jpg (140.99 KiB) Viewed 20709 times

(1) Unscrew the reservoir from the breech block. This will retain the air inside the reservoir. The reservoir is screwed hand tight into the breech, very little effort should be required. The reservoir needs to be empty, so press on the valve until it's empty. Might take some effort, 200bar is a lot of pressure ;) With the air removed, the valve assembly can be unscrewed from the reservoir itself.
(2) Remove the barrel. Two grub screws hold it in place which are located on top of the breech. Unscrew the grub screws a little, and pull out the barrel.
(3) To get to the transferport in the breech block, the part which holds the stock screw needs to be removed. Put a fitting Alan key into the screwhole, and try to get it loose. This will take some effort, the screw is loctited to the breech.
(4) Remove the hammer spring and end cap. The brass end cap is also loctited to the breech, so this wil also take some effort to screw loose.

Time to drill!

First, drill the plastic cap in the valve assembly so there's a 4mm hole in it. Don't drill too far as that'll damage the valve stem, just far enough to get the hole through the plastic. I've used a lathe for this process, so the hole is nice and straight:
T12_upgrade_5.jpg
Drilling the inlet port
T12_upgrade_5.jpg (128.42 KiB) Viewed 20712 times

Next, drill the transfer port in the breech block to the same size, 4mm. Ber very careful not to hit existing the thread inside the hole! Apparently 4.1mm is possible, but I found 4mm to be a tight fit already. A drill press is really indispensible here as the hole needs to be straight and control is needed to make sure no additional damage is done:
T12_upgrade_6.jpg
Drilling the breech
T12_upgrade_6.jpg (113.28 KiB) Viewed 20740 times


With all the nasty drilling out of the way use some compressed air to blow out all debris, and reassemble the action. Except for the hammer spring and cap, those will be replaced with a "high power" version which consists of a hammer weight, stronger spring and a steel screw cap to hold it all into the breech. This is what it looks like. New stuff on top, old stuff at the bottom:
T12_upgrade_7.jpg
Hammer stuff
T12_upgrade_7.jpg (150.79 KiB) Viewed 20709 times


The end result is that I now have a rifle which shoots a 5.5mm JSB Exact Jumbo at around 830fps. This translates to about 24fpe or 33J. Not the 40J (30fpe) I wanted yet, but I have still the option of putting some more pressure on the hammer spring at the cost of more effort to cock the rifle. I'm not sure yet, I'm going to do some grouping tests at distance first. Transfer port wise, there's little more I can do. This T-12 has a new pellet probe which is hollow, and the size of the holes in both barrel and probe are 3.9mm:
hol.jpg
New pellet probe
hol.jpg (175.37 KiB) Viewed 20670 times


UPDATE! After putting some tension on the hammer spring, the T-12 now shoots a 15.9gn JSB Exact Jumbo at 903ft/s. This translates into 28.7fpe, or 39J. Half a turn on the hammer spring tension screw should get me to the 40J I'm looking for.
Webley FX2000 .22
FX T400 .25
FX Monsoon .22 Walnut
FX Cyclone .177 Regulated
FX Biathlon .177 Regulated

I've had:
Pretty much every model FX made :)
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Re: Turning a 10J T-12 into a "full power" T-12

Postby fxuser on Tue May 27, 2008 9:23 am

Hey Wolf,

very good Job to tune up the T12 to a realy true
Powerlevel. If i read this, i became appetite
to by this Rifle and try on this Work. Here in
Germany the 7.5 J Restriction is realy punishment,
to ruin us our Sport. Hope you have in the
Netherland not any fucking Restricton, to use
the realy Potential of this nice FX-Rifle.

I have diversely Airrifles tries, but the FXRifles
are the BEST !!!

Sorry for my bad English, i learning yet.

Greetings fxuser
FX2000 .22 FXCyclone .177 FXranchero .22
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Re: Turning a 10J T-12 into a "full power" T-12

Postby FXpoacher on Tue May 27, 2008 6:10 pm

Hey wolf.
New member here.
You have the same set up as me.
What you need to do is cock the rifle and lock down the bolt in the safe position.
Then screw in the spring screw untill you feel it is tight.
Use 21gr baracudas, and you should be getting between 35-38fpe, (47-51joules).
Gives you about 5-10 shots from a 220bar charge.
But if you use baracudas and hold them around 245-250mtrs per sec, that will give you your 40 joules and about 30-36shots! :)
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Re: Turning a 10J T-12 into a "full power" T-12

Postby PolarWolf on Tue May 27, 2008 7:37 pm

Hi guys, and welcome to the forum.

Fortunately, we don't have any power restrictions in The Netherlands, so all is good there. I try to balance the power with the amount of shots I get from the rifle, so I think I'm going to keep the T-12 as it is. I'm planning to build myself a powerhouse FX using a Typhoon as a base though. Just need to find myself a cheap Typhoon ;)
Webley FX2000 .22
FX T400 .25
FX Monsoon .22 Walnut
FX Cyclone .177 Regulated
FX Biathlon .177 Regulated

I've had:
Pretty much every model FX made :)
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Re: Turning a 10J T-12 into a "full power" T-12

Postby angtr on Mon Jun 30, 2008 10:10 am

Appreciate your sharing, and thank you. I m from New Zealand currently haveing G8 and Cyclone, and they are superbly accuracte.

Cheers

drew
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Re: Turning a 10J T-12 into a "full power" T-12

Postby jon_h on Tue Mar 03, 2009 9:14 pm

Where you can get the upgraded spring and hammer pieces. I cant find anywhere to buy them, not that deal in English anyway. I just want to change that as i have a noisy hammer spring. Many thanks for any help, Jon
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Re: Turning a 10J T-12 into a "full power" T-12

Postby Andyx on Sat May 09, 2009 1:14 pm

Is it the same to tune a Cutlas like this?? What to do with the valve of the tank?
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Re: Turning a 10J T-12 into a "full power" T-12

Postby PolarWolf on Sat May 09, 2009 4:29 pm

Andyx wrote:Is it the same to tune a Cutlas like this?? What to do with the valve of the tank?


Nope, the Cutlas is another design. Check a similar walkthrough for the Cyclone, a Cutlas works the same way.

What about the valve of the tank?
Webley FX2000 .22
FX T400 .25
FX Monsoon .22 Walnut
FX Cyclone .177 Regulated
FX Biathlon .177 Regulated

I've had:
Pretty much every model FX made :)
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Re: Turning a 10J T-12 into a "full power" T-12

Postby sFinn on Fri Aug 14, 2009 4:11 pm

Hello.

I'm about to buy an FX Whisper, is it the same thing to tune up a Whisper to 40J as a T12?

Thanks for the post Polarwolf. :)
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Re: Turning a 10J T-12 into a "full power" T-12

Postby PolarWolf on Fri Aug 14, 2009 4:14 pm

Yeah it's pretty much the same except you'll need to put some more effort in removing the airtube with valve due to the shroud. Once stripped, the procedure is the same.
Webley FX2000 .22
FX T400 .25
FX Monsoon .22 Walnut
FX Cyclone .177 Regulated
FX Biathlon .177 Regulated

I've had:
Pretty much every model FX made :)
User avatar
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Posts: 971
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