Okay, so this might look like "just" any other event achievement, but because of the mechanics on this particular event, it's actually one of the hardest achievements in the game as you can probably judge by its TA ratio. Having to shoot 25 skeets in a row without missing a single one is no mean feat, and the reason why so few people have this achievement is probably because it's long and really quite stressful.
The key to getting this is understanding the slide mechanic properly. When you have a visual on the skeet shooting across the lawn, you have to start moving sideways until it hits your crosshair dead center. Distance doesn't really matter and as long as the skeet is fully in your crosshair, it should hit without a problem. I suggest getting used to how to score hits before moving on, and while you're at it get a feel for the 8 (!) different levels of this challenge.
The trickiest part about this whole thing is the skeets shooting in pairs. Essentially, you have to nip off the first one as quickly as you can, so you have time to register the second one and get clean sweep-hit action on it. The trickiest levels for pairs are 1 (oh the irony), 6 and 7. In those levels, the shooting devices are quite close to you and it's hard to adjust your reflexes that early as the skeet will move past you a lot faster. In levels 2, 3, 4 and 5 you can basically get really close to the devices because they're quite far away, and you should be able to shoot them easily without having to use the A button to sweep your crosshair faster. Use the A button only when you're in serious trouble, because you might confuse yourself.
The 8th level is really easy as it's just 2 single skeets, though the perspective might be confusing at first, as they shoot straight over you. Get used to that before attempting this achievement for real, make sure to do a couple of runs across the entire track. If not, you might find yourself pulling hairs over this last level which is actually one of the easiest once you get used to it.
Good luck, and good shootin'!