G&G Scar-L Semi Auto Issue

[dave38x]

Hey Guys,

Fixing a SCAR-L for a chap at my local site, over the course of which I have basically rebuilt the gearbox. It now has:

SHS 18:1 Gears
SHS Cylinder Head
Deepfire Cylinder
Deepfire Metal Nozzle (Some double feeding issues, these I can sort though)
Element Tappet Plate
SHS M110 Spring
SHS High Torque Motor
Madbull Blue Rubber
Brand new G&G 8mm GB Shell

Everything else is stock.

Basically this is the issue:
After rebuilding the gearbox (fully shimmed, lubed n all) I stuck it in the gun, juiced it up and pulled the trigger. The first trigger pull on semi auto is a single shot. The second trigger pull yields full auto. The third shot is semi, the fourth full auto, etc etc.

Thinking it might be a weak interruptor spring, I took the gearbox out of the gun, stretched the interruptor spring and bolted on the pistol grip. Problem fixed. Semi auto yeilds semi auto.

Having just got the gearbox back into the gun, it's now doing the strange semi-auto-semi-auto pattern again.

My initial guesses are:
Interruptor is snagging on the lower receiver when lifted up
SHS Sector Gear behaving badly
Bolting the pistol grip down has shifted the Gearbox, causing something to snag.

If anyone has any other ideas as to the root cause I'd be very greatful!

[Phatvortex]

Re: G&G Scar-L Semi Auto Issue

Sounds odd. I'm guessing something to do with the selector plate and its interaction with the fire selector. With it all back in the lower receiver, have a look down the side of the gearbox. In semi auto is the selector plate touching the cut-off lever slightly? In full auto it disengages it completely, so I reckon it may be touching it by a gnats cock and causing the odd trouble you're having.

May be a wee session with mr dremel is in order.

[dave38x]

Re: G&G Scar-L Semi Auto Issue

Well I think I've found the two contributing factors:

Number one - The tappet plate was a bit too wide for the shell, resulting in it sticking and causing the sector gear to stop short on semi - this has been rectified
Number two - The motor height allowed for a fair bit of play between the pinion and bevel gear - this has been fixed and has also taken the play out of the gears, again meaning the sector gear stops in the desired position