Hey,
recently discovered your post and agree totally with your choice of parts. I played my MWS for 3 years now as my Summer primary. Just semi, cause in Germany you are not allowed to have full auto on guns over 0.5J. I play it with 0.4g Lonex BBs and a firefly bucking. Shoot nice and straight. I can recommend the first factory hop up arm as well. It provides a stable and constant pressure on the bucking, allowing a precise setting of the Hop. Furthermore, I use the RTS aluminium Bolt, for faster cycling, and the Angry Gun Heavy Buffer.
Recently I had to change the bolt catch lever or whatever it is called, due to deformation of the old, stock one. Now it is a Guns Modify Steel bar. Also I changed the trigger to the one from UAC. More for the looks, than for function
Good to know, that there are other people, having the same issues with the gun.