Nice m16a1's?

Im looking for an m16a1 with nice internals that isn't over 350$ and isn't GBB. I owned a classic army m15a1 for quite a while and it was incredible, but unfortunately I sold it and now it's discontinued. Im trying to find an m16a1 that I can trust, and i've heard that both the CYMAs and the G&Ps have some internal problems. I would go for a Tokyo Marui but not having a metal receiver is a major turnoff.

Am i gonna need to buy one and customize the internals or is there some other brand that's trustworthy?

Thank you kind r/airsoft.