I wasn't doing the same weapon, but I had to kick a couple hundred or so. **THE best way is to be online, because every 5-10 kicks, it will give you an update on the tally, to let you know if what you are doing counts. ***
I went to the desert and kicked some chickens into a dead end and kept kicking them. This can obviously be done in Brightwall as well. I've never seen it require multiple chickens. Just block em in and kick away, and watch the counter grow. I actually walked away hitting the button while I had a quick cig....
A scratch can grow into a fatal wound. One who dwells in Marmo would do well to remember that.
You can definitely kick the same chicken. Aurora is the best place i have found because of the open space and it has several chickens in one location. You may have encountered a glitch if you do not get credit for kicking the same chicken.