Disclaimer You follow the steps herein at your own risk.

1. Field strip the gun separating the barrel and magwell from the main receiver set2. Remove the two screws securing the plastic mag well liner from the mag well and remove the plastic liner itself. Remove the 2 screws that hold the barrel assembly to the mag well.

You should now have the outer barrel and hop unit/inner barrel as one sub unit.

3. Undo the two screws retaining the hop unit in the outer barrel assembly and withdraw the hip unit. (There is a plastic collar glued on the front of the barrel which prevents you from removing the inner barrel smoothly it will need a firm tug to remove the inner barrel/hop unit)

You should now have the hop unit and inner barrel out (notice how the hop unit looks like one piece of moulded plastic with no obvious way of disassembling/servicing it) directly in front of the hop unit is a large thick black plastic washer (you want to save this_

Now comes the point of no return.

4. Remove the hop levers screws and hop bucking from the unit and put them somewhere safe.

5. At the very front off the hop unit is what appears to be a moulding crease running the circumference of the unit. Using the big moulding line as you cutting guide cut through the plastic around the barrel. (Note: the bit you’re cutting off you want to reuse to support the front of the hop unit/barrel)

See the picture below I’ve marked it in red where I placed my cut

This (below) is the result you are aiming for. This bung moulded (or glued on) holds the STD barrel in place.

After cutting it should be free to move forward like (as pictured above)

Now remove the inner barrel and hop (it will be a bit of a tug but it will come free) The only bit you want to save from this is the plastic sleeve with the hop cut out/recess on it everything else is pretty much crap and can be junked.

Take the plastic sleeve and cut the rearmost section off so you cave a circular sleeve approx 1/3 an inch or /8 mm long (this will be used to support and locate your TM barrel in the hop unit.)

Now take your TM barrel and hop rubber and put the rubber on the barrel as you would normally, mark/note where the hop rubber ends and remove the hop rubber. The portion you noted/marked in front of the rubber is where the plastic sleeve will sit you want to rough it up a little with a file to make sure it won’t slip around (later on hen you are satisfied with the

fit/function you may glue it don’t glue it till you are happy as one the superglue it on it sticks like sh*t on a blanket and wont budge)

Now is the trial and error bit. Fit the plastic sleeve on the barrel – it has a grove on the bottom that should be lined up with the grove on the bottom of the TM barrel to ensure the hop cut out is orientated correctly. Fit the hop rubber on the barrel and test fit it in the hop unit.

This will take a few goes to get right as I found the hop rubber is slightly different fit one to the original and deformed a little (causing bb jams on re assembly)

Basically you want the hop rubber in the hop unit with so that when you look down the barrel from the hop unit end it’s near as a prefect circle, no lumps or bits sticking in from the hop rubber (As you would on a normal hop unit) and the supporting sleeve is flush with the hop unit front end. I found that a single layer of electricians insulating tape helped to support the hop rubber and stop it shifting around when firing (mine

was too wide - I cut the excess off)

In the end mine looked like this. (pic above)

Once I was happy with the fit (basically I fitted the hop unit without the bucking or levers to check it wasn’t jamming and test fired a mag to ensure it was working on each mod – it worked a lot better just like that!) I disassembled it again and glued the supporting collar in place then re assembled.

As the inner barrel is a very loose fit in the outer barrel I put a few wraps of insulating tape around the inner barrel at the muzzle end to support it