hi @Daanios
welcome to the forum, and the mws is a great choice in either the CQBR or m4a1 form, it's just whatever look you prefer.
most of us are based in the UK, and it should be noted that the maximum muzzle energy for any full auto or burst fire Airsoft guns is 1.3 joules regardless of BB weight.
personally I think that the easiest way to adjust the energy is with an NPAS which is fitted in the nozzle. this is easily adjusted at crono on the day which is helpful. although multiple upper receivers or bolts is another option, but I am not so familiar with the aftermarket bolts. I'm sure that someone else can fill in the details on that front.