The Real Sword Type 56 series (56, 56-1 and 56-2) are unique in that they are the only AEG rifles manufactured with true 1:1 ratio receivers to the real steel version. Because of this, the gearbox – known as the “T2” – is not a standard (Tokyo Marui spec) Version 3; rather, it is made shorter in the back in order to fit into the receiver. This design concession also means the piston has a somewhat unique shape.
In the event that you damage your factory piston, you can always drop in an aftermarket unit with a few modifications.
In this example, I will be modifying the relatively common SHS 15 tooth piston to fit.
In the following pictures, you can see how the OEM piston interacts with the gearbox shell. There is actually a hole cut out just below the spring guide where the pickup tooth of the piston can obtain clearance under full compression.
It is often mistakenly assumed that the Type 56 piston is shorter than traditional Ver. 2/3 pistons. This is in fact untrue, as they are actually the same length:
The main difference between the two pistons is the Type 56 unit has had material removed on the backside, just above the pickup tooth area:
In order to make an aftermarket piston work, you will need to replicate this cutout so the piston can slip into the hole on the back of the gearbox:
As this is a 15 tooth piston, it is also necessary to remove a single tooth from the front of the piston to make it a 14 tooth setup. If you do not remove this tooth, you run the risk of pre-engagement when the sector gear returns to the pickup position.
Per standard convention, one should also AOE correct (Angle Of Engagement) their pistons to maintain longevity and ensure good meshing. I highly recommend Air Pads for this task. Despite the SHS piston coming equipped with the second to last tooth partially removed, I found it necessary to take it down even further to obtain clearance from the sector gear. Lastly, make sure you glue or epoxy your rack down, and always drop a bit of blue Loctite on the piston head screw upon reassembly.
Voilà!
