I was amazed at the difference too, but the hot groups were the final ones fired that day with the last few rounds of Remington factory ammo.

Will try slow fire groups next range trip and report back.

Generally I've been quite impressed with recent Remington factory ammo... my ZKW465 Hornet shoots well under an inch at 100m just with ordinary 45gr Corelokts, and my Sako L61R .270W shoots just over MOA using plain-vanilla 130gr Corelokt loads.

My only issue is the Remington brass appears to have missed a final neck annealing process (vs the obvious light blue neck annealing colours on Lapua and even Highland brass) and I sometimes experience neck splits on first firing of the factory ammo. I now routinely neck anneal after FLS and trimming and get very good case life.