To delicate to trust - Fostech AR-15 Mg/Al Alloy Upper Receiver Stripped

So I am giant fostech fan and very happy with most of thier products but.... I got this alloy upper incredibly light seems be great quality but mine was slightly off. When assembling it shattered and I’m not talking hair line crack I split it inhalf at about 47ftlbs the barrel pin worked like a can opener and split it in half this was an an upper vise block which not ideal but never problem before I’ve taken an armorers course and this my seven build maybe a fluke maybe unrelated issues but when building 6.5G I want it to be more durable