Well I took her out to the Alberta prairies this week and played with it to 500 meters on a now defunct range that is convieniently located on a friends land. I kept the groups, although left of the point of aim about 10", inside a 6" circle. This was plenty good enough to make me happy, especially being that this was my hunting load, and was worked up with haste, so that i could comfortably hunt with it for the non-trophy antelope season I drew a tag for.
That season opened this morning, and we spotted a herd at 8:00 am. After a half mile belly crawl, i found myself in a position where the tall grass wasn't interfering with the shot. The rangefinder told me 3 times in a row that it was 340 yds, so i believed it. I shot off a bipod in a sitting position and i thought i had missed. The recoil took my eye off the target, and when i reaquired the sight picture, the herd was on the move, none of them appeared to have damage. I watched them for a couple minutes, when one started to sag in the rear end. I thought she was about to tip, but then realised she was just having a piss

. I thought about the situation and knew that i had heard the telltale whack of a high speed bullet finding the sweetspot, so i stood up and the herd vanished. I walked to the last know location of the antelope to see if i could spot any signs of a hit, and found one big one. A doe antelope, dead right there.

A 129 gr Hornady SST at 3000 fps did the trick.
This was the second kill for this rifle, as I also took a 320 yd coyote while scouting the day before.