Got around to working on my TM SCAR-H over the past few days – this is the first batch of photos.
With few guides on the disassembly of the SCAR line, this was a little bit of a guessing game at times (videos with commentary in English from Eagle 6 company in the UK came in very handy)… not to mention the even less information on upgrading them.
Upgrades are already done, but I did forget to post these of the original gearbox until now. We shall start on the SCAR with these.
I would like to preface this by saying that there appear to be many Next Gen/Recoil Shock HK416 DG parts that are compatible with the SCAR-H that I own. Without having taken a look into a SCAR-L or M4 myself, I can’t say for sure – but this is my now-well-informed assumption, based on both lines generally advertised as having “Next Gen Version 2” gearboxes. That being said, there are some differences between both.
Most notable difference is that the gearbox shell is different… but appears to be based off the same mold (thin line remains where HK416 or M4 gearbox shell ends to allow for integration with stock tube), then later modified into a new mold for integrated spring & spring guide, recoil unit.
Cut off lever & anti reversal latch are the same. Good for this project…
Switch assembly looks the same.
Nozzles are practically the same – measured and seem close enough to likely be the same part. Contrary to some of the reports that I read, the SCAR-H nozzle is the same as HK416 DEVGRU (HK416 is same as M4). Both feed in the other gun.
Tappet plate is the same.
Cylinder set is the same.
Test fit a VFC AEG cylinder out curiosity. Fits just the same. However, bevel on inside edge of cylinder causes cylinder head o-ring to not seal correctly with cylinder, massive air leak – original TM cylinder does not have such a large bevel and hence compression is there.
Bolt stop mech is slightly different than M4 – length & width of this one part is only difference.
Plastic wire cover keeps wires from interfering from “bolt stop” empty magazine cut off mechanism on the tight side of the gearbox.
As it turns out, the wire cover is just a snap-in fit. Push through this hole to remove the plate.
Wire harness has spade connectors between lower receiver/gearbox & stock. Allows easier disassembly of SCAR than if the wiring had to be completed dismantled.
Selector plate is different. Ambi selector works differently as to fit in SCAR receiver.
Note recoil weight return spring. There is actually a second, smaller diameter spring inside – shorter & higher tension, but not secured to anything other than being free to float along recoil weight guide pin. Probably rearward buffer for recoil weight, that is what I assume.
Recoil assembly – recoil weight travels on top of gearbox, two metal bars plus one lever reciprocate the mock bolt. I disabled this function after partially snapping the thin little lever. The noise it generated was a bit of a gimmick in my opinion, anyway. Very distinct noise of Marui Next Gen SCAR series Recoil Shock comes from the movement of the mock bolt – mine doesn’t have that sound to it anymore.
Rubber reinforced buffer for recoil weight, should do lots to prevent the top front of the gearbox from cracking.
Reinforcement part (right side) to lower receiver & gearbox shell. Reinforces lower receiver. Front takedown pin sits in here to fasten gearbox to lower, doesn’t secure into upper receiver. The way that it appears to be attached is possibly reinforcing the gearbox shell as well… I would hazard a guess towards this after seeing the reinforcements made to the top half of the gearbox for the recoil weight. Black is right side, not entirely sure why the colour is different than the left side.
Proprietary spring guide. V3 guides from multiple manufacturers do fit in the gearbox, but screw hole is different size. This bolt is one of the two that mounts through the stock hinge plate, so I decided to keep it there as it is part of the assembly holding everything together solid.
Compatibility is good for these gearbox parts – this does mean that I will be able to use my spare clone gearbox for most of the SCAR gearbox parts, if needed in a pinch.