Well, experiece will definetly add to your story appeal. But sniping may be weird to do since you can't just snipe someone. Perhaps going to a shooting range? Using first hand experiece would make the story more realistic but if you can't then there's no problem. Anyway not all your story gonna be about the sniping I presume, but you could research on the internet for the names of parts of guns or gun models. And pictures of guns. Or you can read how it feels to shoot a gun. But you do need basic knowledge so you don't go ; " He loads the gun thingy and shoots it" Some work needs to be done for every story but it'll be worth it in the end!
The best stories are where the writer has done a lot of research into all aspects of their subject. Readers need to believe in the story and they won't unless everything is right.
If you don't want to go out and actually have some type of shooting practice, you need to research. You can't write something other people know about without research.
If I'm writing about nicotine addiction, then I need to research what it feels like, how to get off it, what works, what doesn't.
Because if you don't research, it will seem obnoxious. Especially if it's a huge part of your story.