Why the aggressive reply. You implied that you was not aware in your post. Was just trying to add info. I did not intend to offend.
The OEM supplied argument? Many brands use OEM AEGs then alter them for retail sale as another brand. Heck this is how most things for sale work.
It was never sold with original parts in.
Not really custom, its a Patrol Base Bolster Armouries special: https://www.patrolbase.co.uk/bolster-armouries-aegis-advanced-m4-aeg
So that's the retail AEG. Kind off.