So disregard the above because I bought an M4 stock (M904E) as well.
Also added a ZCI 229MM 6.02 barrel, 60 degree maple leaf, one of the @ak2m4 soft omega nubs and a ZCI CNC hop chamber...which took a it more tweaking than the plastic version but now feeds beautifully, giving a slight boost in fps and above average consistent chrono readings.
That's all I'd recommend doing to these for anyone who's after a primary they can pick up for the price of a low end pistol and yet get decent in game results.
In all honesty I felt a bit silly watching my friend have tons of fun and loads of kills with the £110 (OK plus like £40 in upgrades on top) gun he borrowed from me, while I was having serious issues with my £600 scorpion evo 😑