I have an upper I bought from Delta Team Tactical. At first I had the same grouping problem but after about 200 rounds it seems to have smoothed out. It is definitely picky about ammo though. As long as I stay with American Eagle 75gr it shoots under right at or under MOA and easily hits a 10" plate at 475 yds.
I also have a .223 Wylde upper I bought from them. It also is extremely picky about ammo. Some of the reloads I did with it would not hit a 8 1/2x11 target at 100yds. One does well under MOA out to 300yds.
Both barrels seem to want a good break in period.
I have not started reloading for the Valkyrie yet.
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