Acloco I haven't shot a 308 at 1000yds in my life, Always had something considerably faster. The reason I haven't is i was told out of short barrels like the OP mentioned it is almost impossible to keep a 168 supersonic at 1000. Has this changed? I would love to be able to shoot my 308 1000yds.
As others have stated, does not need to be supersonic to hit the paper or the steel.
At least once, every year, I help out with some close to 1K training. Rain/Shine/Snow/or Wind - we shoot.
At the 20" and under barrel length, it is a maybe they will hit anything past 800. Have seen ONE 18" barrel that would still get the job done at 900, but nothing at 1K.
22" barrel, as the original poster is using, is probable at 1K - all depends on the barrel.
LOTS of Hornady TAP 168's are the norm. Occasionally see a 30/06 in the mix. ONE 7 Mag. Starting to see 6.5 creeds.
For my area, just like the BR shooters, the wind call is the main deciding factor.
In our exercise, we also find out who KNOWS their equipment (90% don't), who has GOOD experience and/or previous training, and the occasional lucky person who has little experience, but ends up being a rockstar during quals.
ebb - funny that you mention speed. At the end of the week, the instructor provides some last tidbits of info. One of the items is - YOU cannot overcome wind/distance/you....with anything. I raised my hand two years ago (and got "the look").....I said, one thing will help with two of those items.....SPEED! He smiled, chuckled, and said, yes........but the ought EIGHT is what most have.....play the hand you are dealt......and KNOW IT!