The replica give the user the ability to replace the spring without removing the gearbox from the receiver. It is faster here than in many such solutions, but you have to have a tool to unscrews the ring on the stock guide. It is done the same as in a firearm - I used a dedicated key to do it. If you do not have one you have to cope differently. In the photo: the ring fully unscrewed and back plate of the receiver moved with a finger. You can rotate (unscrew) the stock guide. This solution is not unique - there are others available on the marker that operate very similarly.
After removing the guide, you gain access to the rear part of the gearbox and you can unlock and pull the spring guide out together with the spring using an Allen key. During this operation, in our unit, it turned out that the electric wires were damaged. I have no idea if it's the fault of a sloppy factory assembly or if someone took the rifle apart before we did. In any case, when putting the replica back together, after replacing the spring for example, you have to pay special attention to the wires.
Taking the replica apart is typical. A front pin connecting the receiver parts should be removed (it will not get lost - it is secured with a cotter pin). Then we slide the upper receiver forward. It may be necessary to manipulate the bolt catch a bit - it can get locked in the notch in the upper receiver. The rifle without previously dismounted stock guide and the upper receiver:
The bolt catch must also be removed. You don't need to use a hammer here. On the side of the pistol grip is a setting screw, which also acts a the axle of the bolt catch.
The setting screw has a head compatible with a flat head screwdriver.
Next, we disassemble the pistol grip, take out the rear pin and the pin above the trigger, than unscrew and remove both fire selector switches. Beware of bearing balls and springs - they are on both sides!
The gearbox after removing it from the receiver with the dummy bolt still attached.
And from the other side:
In both of the above photographs you can see gears lying separately - these are parts working freely in the sockets indicated by red arrows. After removing the gearbox from the receiver they simply fall out. The blue arrow indicates the place which should be taped slightly to dismantle the other gears. The green arrow, on the other hand, shows the part that holds the dummy bolt. When opening the gearbox, for example in Specna Arms replicas, it must be unscrewed, because it covers access to one of the screws connecting the gearbox halves. Here it can stay in its place - just hold it in the upper position.
Let's go back to the left side of the gearbox. The the selector plate is in a standard shape for the AR-15 replicas. It has a plate with additional external contact surfaces of the trigger switch, which serve as a second protection against accidental firing.
Well, in the Safe position, you can sometimes overcome the mechanical trigger lock and press it. When the replica has the additional contact surfaces described above, it will not fire as the plate is moved forward and the circuit is interrupted. This is an old solution as Tokyo Marui developed in in the 1990s. Currently, manufacturers often save on materials and use trigger switches without additional contact surfaces. Such an switch is always live. A forceful pull of the trigger results in a shot. Even when the fire selector switch is in the Safe position. It is worth noting that additional side contact surfaces do not limit the use of a mosfet in the slightest.
The gearbox
In the BDR's gearbox it is often referred to in the Internet as the "EMG Special Edition Extra Smooth Gearbox", but I have the impression that it is pure marketing. It seems to me that this is a standard APS mechanism.
The frame itself is a V2, slightly modified for the needs of a blowback system. In the designs of many other manufacturers, the movement of the piston is transferred to the dummy bolt vie a port in the upper part of the frame. This often requires the use of dedicated pistons with a special latch (see ICS pistons for EBB replicas by this manufacturer). APS uses two ports in the right half of the gearbox. The dummy bolt enters the ports and is moved by the working piston. What is important, the piston is standard, without any modifications. The allows for using standard pistons by any manufacturer.
Internal parts of the gearbox.
Both the parts and the assembly method do not raise any objections. Even the shimming of the gears of the tested unit was perfect. Maybe that's why it is called "extra smooth"? If I had to complain about something, I would point out a significant amount of lubricant. It was obvious that the gears stick to each other, which unnecessarily strains the motor, increases the power consumption and affects the rate of fire.
The pneumatic system consists mostly of typical parts.
Chromed typu 2 cylinder.
The cylinder head is plastic.
Metal sealed nozzle is 21.65 mm long.
A full-width teeth, the last tooth made of steel.
Polymer directional piston head, but is has a full ball bearing.
A spring with irregular coils and a spring guide with a bearing.
The spring guide has four locking flaps.
Steel, sintered gears. Standard anti-reversing latch. A plastic delayer on the sector gear.
A typical tappet plate.
A long type motor with no markings.
A typical trigger switch, moderately rigid wires in transparent insulation. A cartridge fuse in a typical plastic housing. A Tamiya mini plug.
Vertical, straight, so-called speed trigger. It has a positive effect on the speed and accuracy of shots.
Next page - the inner barrel, the Hop-Up chamber and the magazine.
