Problems with New 6.5 Grendel Upper Build

[Steamburn]

The coating on the steel cases melt and leave a goo inside the chamber. Try first cleaning it well with a bronze wire brush and any of the magic solvents (Hopes9, CLP, and acetone) yes, acetone to get rid of the melted goo. Try also Goo-Gone.
Once clean, test again with the Hornady brass cases. If still a problem, then a call to Alexander Arms for sure.