by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2

Today’s report contains special instructions for the disassembly of a Feinwerkbau 150 air rifle — for those few places where it departs from the FWB 300 instructions presented in Parts 1 and 2. It was translated and written for us by reader CptKlotz.

If you’d like to write a guest post for this blog, please email me.

Over to you, CptKlotz.

This report covers:

  • Additional information for disassembling FWB 150 rifles
    Trigger blade
    Ratchet unit
    Powerplant disassembly — potential danger!

This article was originally published on the German co2air forums ( It was created by the users Pellet (original text guide), Paramags (additional information and FWB150 details ) and boerni (photos and forum post). They kindly gave me permission to translate their guide so people who can’t read German can use it as well. The original forum post can be found here.

Translation by Stephan Szlosze (CptKlotz). Any text in italics is a comment from the translator.

Disclaimer: If you decide to work on your gun, you do so at your own risk. Neither Pyramyd Air,, the authors or I will accept any responsibility for injury or damage to you, your rifle or your equipment. Please read the guide carefully and proceed with caution.

Additional information for disassembling FWB 150 rifles

The action of the FWB 150 rifle is almost identical to that of the 300/300S. Still, there are some crucial differences that need to be kept in mind.

Steps 1 through 8 of the FWB300 guide apply to the 150 as well. The following steps are different and will be explained here.

Trigger blade

Removing the 150’s trigger blade is not as easy as it is on the newer models. This is not a problem, though, since removing it is not required for disassembly. When removing the trigger/ratchet unit, make sure the screwdriver’s blade is exactly the right size. On the old models, these screws are extremely tight and it is very easy to damage the screw’s head.

FWB 150 cocking lever
The cocking lever should be unlatched to make it easier to remove the screw.

First to come off is the cocking lever. Unlatch it before trying to remove the pivot, as that takes the tension off the screw.

Ratchet unit

Next to come off is the ratchet unit that contains the trigger mechanism. The ratchet unit prevents the sliding compression chamber from closing before the action is cocked. It interfaces with the piston so it can hold it in position before the sear has been set.

FWB 150 ratchet unit off
The ratchet unit that contains the trigger mechanism is off the gun.

Now that the ratchet unit is off the rifle, you can use the opportunity to clean and lubricate it.

Important: When you reassemble the rifle, make sure the ratchet unit is making proper contact with the piston’s notch.

FWB 150 piston notch
The ratchet unit (below) has a metal tab that engages the piston notch (arrow). Make sure they go together correctly when the gun is assembled.

Powerplant disassembly — potential danger!

Now we come to the most significant difference between the FWB 150 and the FWB 300. The FWB 150 does not have an anti-beartrap device like the 300. This means there is no leaf spring and no pin to secure the powerplant. This makes removing the parts of the powerplant much harder! It is almost impossible to safely do so without the help of a second person!

FWB 150 powerplant
The 150 action has no anti-beartrap device. The 17mm screw (arrow) is all that holds the powerplant together. When it comes out, the parts want to fly apart under spring tension.


One person should press the action against the floor with the muzzle pointing up. The second person uses the 17mm wrench to carefully remove the screw that holds the powerplant together. Once it comes out the spring is only held in place by muscle power bearing down on the gun! Release the pressure slowly to let the powerplant components slide out of the action.

FWB 150 powerplant open
The screw has been removed (upper left) and the mainspring is relaxed.

Important: When assembling the action, the second person has to make sure the end cap is aligned properly with the action. Otherwise, the threads can be damaged when reinserting the screw. Again, do not attempt to do this by yourself. It is very difficult to install the parts correctly while working against the power of the mainspring.

FWB 150 spring
An original FWB 150 mainspring looks like this. 

If your rifle is still in its original state, you will find a single spring.
FWB 150 spring vs 300 spring
The 150 spring (above) compared to the 300 spring.

The spring for the 150 is not available anymore, but it is possible to use the dual mainsprings of the 300. You will, however, have to remove the linking piece (the solid piece in the center of the 300 spring that holds the two smaller springs together) as it will not fit over the spring guide inside the end cap, thus making cocking the rifle impossible.

Since the springs will always be under preload, they will work fine without the linking piece.

FWB 150 end cap
The spring guide on the FWB 150 end cap is too large to fit over the FWB 300 spring connector. Just leave it out and everything will fit fine.

[Editor’s note: I’ve owned both a FWB 300S and a FWB 150. At first they seemed very similar, other than the 150 stock being shaped more like a sporter stock than a target stock. But comparing them side by side, it becomes clear what a vast improvement the 300 is! It’s smoother, has less felt recoil/vibration and has a much better trigger than the 150, in my opinion. Since I am more of a shooter than a collector, I sold my 150 and kept the 300S. I’m just telling you this to let you know that these two very similar target rifles do have some significant performance differences.

My thanks to Stephan Szlosze for his diligent work in assembling this three-part report.]