Seeing bullet holes is a hit miss proposition at 1000yds. 600yds would be easier naturally, but the mirage will still raise havoc with you.
But to simply answer your question outright..... yes. In certain conditions only though. The Bushnell glass is good enough to do it at 1000yd if the bullet holes are in the white only and the conditions are right. I've seen them using Bushnell, Kowa, and Swarovski glass before. But it depends on the mirage, time of day, and position of the sun. I attend 18-20 1000yd matches a year and I might be able to see holes on maybe 5 different occasions. And that's only at certain times during any one partcular match.
Plus the other thing is your eyes. I know by using an adjsutable scope you should be able to see as good as the next guy looking through the same scope, but it's simply not the case.
A perfect example of this was back in 98 or 99 at the VA 1000yd range I was spotting for Dave Tooley and Rick Piccaretta was spotting for the shooter on the bench just to the right of Dave. Well Dave fired really fast and Rick made a comment that Dave had 4 bullet holes in the lower left hand corner of the 4" white square that we have in the middle of our X ring for sighting purposes. I was using Dave's Kowa bigeye's to look through and couldn't pick them out. I have been able to see holes at other times using this setup before. I ask Rick if I could look through the Swarovski scope he was using, and I couldn't see the holes he was talking about.
After the target was scored, Rick was 100% correct! But I couldn't see them using the same scope.
I've also seen a man call 6mm bullet holes in the white at 1000yd using a 12-42X Nightforce scope on approx 28-30X. He called the location, approx group size, and the score sitting at the bench looking through the scope. He was right on, after that target was brought back and scored also. I've never been able to see 6mm holes ever. So yes it can be done, but you may or maynot be able to do it yourself.