Externals are amazing, LCT are known for their high quality externals and the AK was built to Russian design documents so its pretty much as accurate as you can get to the real one, which also includes a massive compatibility spectrum for real steel parts.
My particular GK-105 from WGC shot itself to bits 3 mags in. I know this is a common issue with the new generations of GHK AKs due to a lack of good quality control and good manufacturing processes. I was one of the lucky ones and managed to resolve my issues by changing the hop-up unit to a maple leaf CNC one and slowly filing down the feedramp to ensure that everything was aligned and fit correctly. Though this should be something that comes correct from the factory considering the price you're paying. I have listed some confirmed common GHK Faults below that you should keep an eye out for as if you're unlucky and suffer from a few of these issues you will have a very expensive paper weight or wall trophy.
Only reason I'm giving it 4 stars is due to the fact that the externals make it amazing and I was one of the lucky ones that got the newer generations to work. If it weren't for those 2 points this would be a 1 star gun. A very expensive non functioning weapon.
GHK AK QC issues + common faults
Autosear groove cut too shallow causing the spring to dislodge
Dislodged disconnector (trigger sear) spring
Borked front trunnion indicators
Damage along top of hop unit
Drooped outer barrel
Disconnector (trigger sear) failure
Other rare QC failures
Valve knocker hook failure