Agree, good bench Technique and follow through is vitally important when shooting longer ranges.

The higher the BC - usually the faster the required twist rate.

BT bullets normally require to be super sonic to maintain stability and transition into subsonic flight poorly, while flat based bullets transition into subsonic speeds with greater remaining accuracy. I've read this is the reason why the record 1,000yard BR groups were shot with flat based bullets, to maintain better accuracy over greater velocity changes.

Seems to me the 1.587", 5 shot group a few years ago was shot with 187gr. FB bullets (4 were in 1-1/4"). A .30 Wildcat- .30 Baer, I think. That record was then trashed with a 1.3" something more recently. Prior, a 3" group was the record, me thinks. Mind you, this was ONLY 1,000yards.

Getting the hits on a silhouette at 1 mile is an accomplishment for sure, especially with a factory rifle and 'seemingly' non-sniper or non-BR shooters.