Who makes the strongest upper receiver?

[Joseph5]

I got the Sun Devil billet receiver set when I assembled my 6.5 Grendel. It has very thick upper receiver walls and the upper to lower fit was very tight! No wiggle or play at all without using the built in tightening screw. I have to tap out the receiver pins to disassemble it. That is how tight the fit is. The Cerakote job left a lot to be desired. It was rubbing off just putting the BCG into the upper and moving it back and forth. I suspect that it missed getting baked after application. I would not hesitate to buy another set from them, just an anodized one though. Another receiver set I have heard nothing but good about are the ones from Precision Firearms. They are finished exceptionally well and have nice thick receiver walls and fit togethoer very tight.