Rounds getting buffeted at transonic...That's the theory anyway. Like the old X1 experimental plane being pushed around in the dive as it approached Mach 1. On breaking the sound barrier everything was suddenly smooth again.
Shooting 1,000yds in F Class competition those of us who use .223 notice the group sizes start increasing after 900yds. More than predicted by the MOA of your gun. We can still group at 1000 but never win against the 308 guys, even with BC's higher than theirs. Less than 900 is a much more level playing field. The Australian F Class champion who shoots in our state does not use 223 at serious long range competition. An 80gn FMJBT 223 exits a 30" barrel at about 2960fps, drops below 1300fps by 900yds and crosses the sound barrier at 1100yds.
I am thinking the sound barrier buffeting for a 223 starts as the round drops below 1300fps and builds to the point where bullets will tumble as they fall out of the sky. Never shot anything beyond 1000yds so can't comment on when of if all bullets actually tumble as they go unstable. Even if a round does tumble the idea that it still groups roughly at what you are shooting at makes sense, just a bigger group.
Shooting 1,000yds in F Class competition those of us who use .223 notice the group sizes start increasing after 900yds. More than predicted by the MOA of your gun. We can still group at 1000 but never win against the 308 guys, even with BC's higher than theirs. Less than 900 is a much more level playing field. The Australian F Class champion who shoots in our state does not use 223 at serious long range competition. An 80gn FMJBT 223 exits a 30" barrel at about 2960fps, drops below 1300fps by 900yds and crosses the sound barrier at 1100yds.
I am thinking the sound barrier buffeting for a 223 starts as the round drops below 1300fps and builds to the point where bullets will tumble as they fall out of the sky. Never shot anything beyond 1000yds so can't comment on when of if all bullets actually tumble as they go unstable. Even if a round does tumble the idea that it still groups roughly at what you are shooting at makes sense, just a bigger group.